thin-film transistor tft display quotation

A thin-film-transistor liquid-crystal display (TFT LCD) is a variant of a liquid-crystal display that uses thin-film-transistor technologyactive matrix LCD, in contrast to passive matrix LCDs or simple, direct-driven (i.e. with segments directly connected to electronics outside the LCD) LCDs with a few segments.

In February 1957, John Wallmark of RCA filed a patent for a thin film MOSFET. Paul K. Weimer, also of RCA implemented Wallmark"s ideas and developed the thin-film transistor (TFT) in 1962, a type of MOSFET distinct from the standard bulk MOSFET. It was made with thin films of cadmium selenide and cadmium sulfide. The idea of a TFT-based liquid-crystal display (LCD) was conceived by Bernard Lechner of RCA Laboratories in 1968. In 1971, Lechner, F. J. Marlowe, E. O. Nester and J. Tults demonstrated a 2-by-18 matrix display driven by a hybrid circuit using the dynamic scattering mode of LCDs.T. Peter Brody, J. A. Asars and G. D. Dixon at Westinghouse Research Laboratories developed a CdSe (cadmium selenide) TFT, which they used to demonstrate the first CdSe thin-film-transistor liquid-crystal display (TFT LCD).active-matrix liquid-crystal display (AM LCD) using CdSe TFTs in 1974, and then Brody coined the term "active matrix" in 1975.high-resolution and high-quality electronic visual display devices use TFT-based active matrix displays.

The liquid crystal displays used in calculators and other devices with similarly simple displays have direct-driven image elements, and therefore a voltage can be easily applied across just one segment of these types of displays without interfering with the other segments. This would be impractical for a large display, because it would have a large number of (color) picture elements (pixels), and thus it would require millions of connections, both top and bottom for each one of the three colors (red, green and blue) of every pixel. To avoid this issue, the pixels are addressed in rows and columns, reducing the connection count from millions down to thousands. The column and row wires attach to transistor switches, one for each pixel. The one-way current passing characteristic of the transistor prevents the charge that is being applied to each pixel from being drained between refreshes to a display"s image. Each pixel is a small capacitor with a layer of insulating liquid crystal sandwiched between transparent conductive ITO layers.

The circuit layout process of a TFT-LCD is very similar to that of semiconductor products. However, rather than fabricating the transistors from silicon, that is formed into a crystalline silicon wafer, they are made from a thin film of amorphous silicon that is deposited on a glass panel. The silicon layer for TFT-LCDs is typically deposited using the PECVD process.

Polycrystalline silicon is sometimes used in displays requiring higher TFT performance. Examples include small high-resolution displays such as those found in projectors or viewfinders. Amorphous silicon-based TFTs are by far the most common, due to their lower production cost, whereas polycrystalline silicon TFTs are more costly and much more difficult to produce.

The twisted nematic display is one of the oldest and frequently cheapest kind of LCD display technologies available. TN displays benefit from fast pixel response times and less smearing than other LCD display technology, but suffer from poor color reproduction and limited viewing angles, especially in the vertical direction. Colors will shift, potentially to the point of completely inverting, when viewed at an angle that is not perpendicular to the display. Modern, high end consumer products have developed methods to overcome the technology"s shortcomings, such as RTC (Response Time Compensation / Overdrive) technologies. Modern TN displays can look significantly better than older TN displays from decades earlier, but overall TN has inferior viewing angles and poor color in comparison to other technology.

Most TN panels can represent colors using only six bits per RGB channel, or 18 bit in total, and are unable to display the 16.7 million color shades (24-bit truecolor) that are available using 24-bit color. Instead, these panels display interpolated 24-bit color using a dithering method that combines adjacent pixels to simulate the desired shade. They can also use a form of temporal dithering called Frame Rate Control (FRC), which cycles between different shades with each new frame to simulate an intermediate shade. Such 18 bit panels with dithering are sometimes advertised as having "16.2 million colors". These color simulation methods are noticeable to many people and highly bothersome to some.gamut (often referred to as a percentage of the NTSC 1953 color gamut) are also due to backlighting technology. It is not uncommon for older displays to range from 10% to 26% of the NTSC color gamut, whereas other kind of displays, utilizing more complicated CCFL or LED phosphor formulations or RGB LED backlights, may extend past 100% of the NTSC color gamut, a difference quite perceivable by the human eye.

In 2004, Hydis Technologies Co., Ltd licensed its AFFS patent to Japan"s Hitachi Displays. Hitachi is using AFFS to manufacture high end panels in their product line. In 2006, Hydis also licensed its AFFS to Sanyo Epson Imaging Devices Corporation.

A technology developed by Samsung is Super PLS, which bears similarities to IPS panels, has wider viewing angles, better image quality, increased brightness, and lower production costs. PLS technology debuted in the PC display market with the release of the Samsung S27A850 and S24A850 monitors in September 2011.

TFT dual-transistor pixel or cell technology is a reflective-display technology for use in very-low-power-consumption applications such as electronic shelf labels (ESL), digital watches, or metering. DTP involves adding a secondary transistor gate in the single TFT cell to maintain the display of a pixel during a period of 1s without loss of image or without degrading the TFT transistors over time. By slowing the refresh rate of the standard frequency from 60 Hz to 1 Hz, DTP claims to increase the power efficiency by multiple orders of magnitude.

Due to the very high cost of building TFT factories, there are few major OEM panel vendors for large display panels. The glass panel suppliers are as follows:

External consumer display devices like a TFT LCD feature one or more analog VGA, DVI, HDMI, or DisplayPort interface, with many featuring a selection of these interfaces. Inside external display devices there is a controller board that will convert the video signal using color mapping and image scaling usually employing the discrete cosine transform (DCT) in order to convert any video source like CVBS, VGA, DVI, HDMI, etc. into digital RGB at the native resolution of the display panel. In a laptop the graphics chip will directly produce a signal suitable for connection to the built-in TFT display. A control mechanism for the backlight is usually included on the same controller board.

The low level interface of STN, DSTN, or TFT display panels use either single ended TTL 5 V signal for older displays or TTL 3.3 V for slightly newer displays that transmits the pixel clock, horizontal sync, vertical sync, digital red, digital green, digital blue in parallel. Some models (for example the AT070TN92) also feature input/display enable, horizontal scan direction and vertical scan direction signals.

New and large (>15") TFT displays often use LVDS signaling that transmits the same contents as the parallel interface (Hsync, Vsync, RGB) but will put control and RGB bits into a number of serial transmission lines synchronized to a clock whose rate is equal to the pixel rate. LVDS transmits seven bits per clock per data line, with six bits being data and one bit used to signal if the other six bits need to be inverted in order to maintain DC balance. Low-cost TFT displays often have three data lines and therefore only directly support 18 bits per pixel. Upscale displays have four or five data lines to support 24 bits per pixel (truecolor) or 30 bits per pixel respectively. Panel manufacturers are slowly replacing LVDS with Internal DisplayPort and Embedded DisplayPort, which allow sixfold reduction of the number of differential pairs.

The bare display panel will only accept a digital video signal at the resolution determined by the panel pixel matrix designed at manufacture. Some screen panels will ignore the LSB bits of the color information to present a consistent interface (8 bit -> 6 bit/color x3).

With analogue signals like VGA, the display controller also needs to perform a high speed analog to digital conversion. With digital input signals like DVI or HDMI some simple reordering of the bits is needed before feeding it to the rescaler if the input resolution doesn"t match the display panel resolution.

Kawamoto, H. (2012). "The Inventors of TFT Active-Matrix LCD Receive the 2011 IEEE Nishizawa Medal". Journal of Display Technology. 8 (1): 3–4. Bibcode:2012JDisT...8....3K. doi:10.1109/JDT.2011.2177740. ISSN 1551-319X.

Brody, T. Peter; Asars, J. A.; Dixon, G. D. (November 1973). "A 6 × 6 inch 20 lines-per-inch liquid-crystal display panel". 20 (11): 995–1001. Bibcode:1973ITED...20..995B. doi:10.1109/T-ED.1973.17780. ISSN 0018-9383.

K. H. Lee; H. Y. Kim; K. H. Park; S. J. Jang; I. C. Park & J. Y. Lee (June 2006). "A Novel Outdoor Readability of Portable TFT-LCD with AFFS Technology". SID Symposium Digest of Technical Papers. AIP. 37 (1): 1079–82. doi:10.1889/1.2433159. S2CID 129569963.

Kim, Sae-Bom; Kim, Woong-Ki; Chounlamany, Vanseng; Seo, Jaehwan; Yoo, Jisu; Jo, Hun-Je; Jung, Jinho (15 August 2012). "Identification of multi-level toxicity of liquid crystal display wastewater toward Daphnia magna and Moina macrocopa". Journal of Hazardous Materials. Seoul, Korea; Laos, Lao. 227–228: 327–333. doi:10.1016/j.jhazmat.2012.05.059. PMID 22677053.

A thin-film transistor (TFT) is a special type of field-effect transistor (FET) where the transistor is thin relative to the plane of the device.substrate. A common substrate is glass, because the traditional application of TFTs is in liquid-crystal displays (LCDs). This differs from the conventional bulk metal oxide field effect transistor (MOSFET), where the semiconductor material typically is the substrate, such as a silicon wafer.

TFTs can be fabricated with a wide variety of semiconductor materials. Because it is naturally abundant and well understood, amorphous or polycrystalline silicon was historically used as the semiconductor layer. However, because of the low mobility of amorphous siliconcadmium selenide,metal oxides such as indium gallium zinc oxide (IGZO) or zinc oxide,organic semiconductors,carbon nanotubes,metal halide perovskites.

Because TFTs are grown on inert substrates, rather than on wafers, the semiconductor must be deposited in a dedicated process. A variety of techniques are used to deposit semiconductors in TFTs. These include chemical vapor deposition (CVD), atomic layer deposition (ALD), and sputtering. The semiconductor can also be deposited from solution,printing

Some wide band gap semiconductors, most notable metal oxides, are optically transparent.electrodes, such as indium tin oxide (ITO), some TFT devices can be designed to be completely optically transparent.head-up displays (such as on a car windshield).The first solution-processed TTFTs, based on zinc oxide, were reported in 2003 by researchers at Oregon State University.Universidade Nova de Lisboa has produced the world"s first completely transparent TFT at room temperature.

The best known application of thin-film transistors is in TFT LCDs, an implementation of liquid-crystal display technology. Transistors are embedded within the panel itself, reducing crosstalk between pixels and improving image stability.

As of 2008LCD TVs and monitors use this technology. TFT panels are frequently used in digital radiography applications in general radiography. A TFT is used in both direct and indirect capturemedical radiography.

The most beneficial aspect of TFT technology is its use of a separate transistor for each pixel on the display. Because each transistor is small, the amount of charge needed to control it is also small. This allows for very fast re-drawing of the display.

In February 1957, John Wallmark of RCA filed a patent for a thin film MOSFET in which germanium monoxide was used as a gate dielectric. Paul K. Weimer, also of RCA implemented Wallmark"s ideas and developed the thin-film transistor (TFT) in 1962, a type of MOSFET distinct from the standard bulk MOSFET. It was made with thin films of cadmium selenide and cadmium sulfide. In 1966, T.P. Brody and H.E. Kunig at Westinghouse Electric fabricated indium arsenide (InAs) MOS TFTs in both depletion and enhancement modes.

The idea of a TFT-based liquid-crystal display (LCD) was conceived by Bernard J. Lechner of RCA Laboratories in 1968.dynamic scattering LCD that used standard discrete MOSFETs, as TFT performance was not adequate at the time.T. Peter Brody, J. A. Asars and G. D. Dixon at Westinghouse Research Laboratories developed a CdSe (cadmium selenide) TFT, which they used to demonstrate the first CdSe thin-film-transistor liquid-crystal display (TFT LCD).electroluminescence (EL) in 1973, using CdSe.active-matrix liquid-crystal display (AM LCD) using CdSe in 1974, and then Brody coined the term "active matrix" in 1975.

A breakthrough in TFT research came with the development of the amorphous silicon (a-Si) TFT by P.G. le Comber, W.E. Spear and A. Ghaith at the University of Dundee in 1979. They reported the first functional TFT made from hydrogenated a-Si with a silicon nitride gate dielectric layer.research and development (R&D) of AM LCD panels based on a-Si TFTs in Japan.

By 1982, Pocket TVs based on AM LCD technology were developed in Japan.Fujitsu"s S. Kawai fabricated an a-Si dot-matrix display, and Canon"s Y. Okubo fabricated a-Si twisted nematic (TN) and guest-host LCD panels. In 1983, Toshiba"s K. Suzuki produced a-Si TFT arrays compatible with CMOS integrated circuits (ICs), Canon"s M. Sugata fabricated an a-Si color LCD panel, and a joint Sanyo and Sanritsu team including Mitsuhiro Yamasaki, S. Suhibuchi and Y. Sasaki fabricated a 3-inch a-SI color LCD TV.

The first commercial TFT-based AM LCD product was the 2.1-inch Epson ET-10Hitachi research team led by Akio Mimura demonstrated a low-temperature polycrystalline silicon (LTPS) process for fabricating n-channel TFTs on a silicon-on-insulator (SOI), at a relatively low temperature of 200°C.Hosiden research team led by T. Sunata in 1986 used a-Si TFTs to develop a 7-inch color AM LCD panel,Apple Computers.Sharp research team led by engineer T. Nagayasu used hydrogenated a-Si TFTs to demonstrate a 14-inch full-color LCD display,electronics industry that LCD would eventually replace cathode-ray tube (CRT) as the standard television display technology.notebook PCs.IBM Japan introduced a 12.1-inch color SVGA panel for the first commercial color laptop by IBM.

TFTs can also be made out of indium gallium zinc oxide (IGZO). TFT-LCDs with IGZO transistors first showed up in 2012, and were first manufactured by Sharp Corporation. IGZO allows for higher refresh rates and lower power consumption.polyimide substrate.

Brody, T. Peter (November 1984). "The Thin Film Transistor - A Late Flowering Bloom". IEEE Transactions on Electron Devices. 31 (11): 1614–1628. Bibcode:1984ITED...31.1614B. doi:10.1109/T-ED.1984.21762. S2CID 35904114.

Petti, Luisa; Münzenrieder, Niko; Vogt, Christian; Faber, Hendrik; Büthe, Lars; Cantarella, Giuseppe; Bottacchi, Francesca; Anthopoulos, Thomas D.; Tröster, Gerhard (2016-06-01). "Metal oxide semiconductor thin-film transistors for flexible electronics". Applied Physics Reviews. 3 (2): 021303. Bibcode:2016ApPRv...3b1303P. doi:10.1063/1.4953034.

Wager, John. OSU Engineers Create World"s First Transparent Transistor Archived 2007-09-15 at the Wayback Machine. College of Engineering, Oregon State University, Corvallis, OR: OSU News & Communication, 2003. 29 July 2007.

Fortunato, E. M. C.; Barquinha, P. M. C.; Pimentel, A. C. M. B. G.; Gonçalves, A. M. F.; Marques, A. J. S.; Pereira, L. M. N.; Martins, R. F. P. (March 2005). "Fully Transparent ZnO Thin-Film Transistor Produced at Room Temperature". Advanced Materials. 17 (5): 590–594. Bibcode:2005AdM....17..590F. doi:10.1002/adma.200400368. S2CID 137441513.

Brody, T. P.; Kunig, H. E. (October 1966). "A HIGH‐GAIN InAs THIN‐FILM TRANSISTOR". Applied Physics Letters. 9 (7): 259–260. Bibcode:1966ApPhL...9..259B. doi:10.1063/1.1754740. ISSN 0003-6951.

Kawamoto, H. (2012). "The Inventors of TFT Active-Matrix LCD Receive the 2011 IEEE Nishizawa Medal". Journal of Display Technology. 8 (1): 3–4. Bibcode:2012JDisT...8....3K. doi:10.1109/JDT.2011.2177740. ISSN 1551-319X.

Brody, T. Peter; Asars, J. A.; Dixon, G. D. (November 1973). "A 6 × 6 inch 20 lines-per-inch liquid-crystal display panel". 20 (11): 995–1001. Bibcode:1973ITED...20..995B. doi:10.1109/T-ED.1973.17780. ISSN 0018-9383.

Mimura, Akio; Oohayashi, M.; Ohue, M.; Ohwada, J.; Hosokawa, Y. (1986). "SOI TFT"s with directly contacted ITO". IEEE Electron Device Letters. 7 (2): 134–6. Bibcode:1986IEDL....7..134M. doi:10.1109/EDL.1986.26319. ISSN 0741-3106. S2CID 36089445.

Sunata, T.; Yukawa, T.; Miyake, K.; Matsushita, Y.; Murakami, Y.; Ugai, Y.; Tamamura, J.; Aoki, S. (1986). "A large-area high-resolution active-matrix color LCD addressed by a-Si TFT"s". 33 (8): 1212–1217. Bibcode:1986ITED...33.1212S. doi:10.1109/T-ED.1986.22644. ISSN 0018-9383. S2CID 44190988.

Sunata, T.; Miyake, K.; Yasui, M.; Murakami, Y.; Ugai, Y.; Tamamura, J.; Aoki, S. (1986). "A 640 × 400 pixel active-matrix LCD using a-Si TFT"s". IEEE Transactions on Electron Devices. 33 (8): 1218–21. Bibcode:1986ITED...33.1218S. doi:10.1109/T-ED.1986.22645. ISSN 0018-9383. S2CID 6356531.

Nagayasu, T.; Oketani, T.; Hirobe, T.; Kato, H.; Mizushima, S.; Take, H.; Yano, K.; Hijikigawa, M.; Washizuka, I. (October 1988). "A 14-in.-diagonal full-color a-Si TFT LCD". Conference Record of the 1988 International Display Research Conference: 56–58. doi:10.1109/DISPL.1988.11274. S2CID 20817375.

Manufacturer of standard & custom touch screen displays & thin film transistor touchscreen monitors. Features include 17 in. to 23 in. LCD, rugged steel & aluminum construction, optional resistive or capacitive touch-screens, light textured powder coated black color, contrast filters, transmissive daylight modification, hard coated vandal shields, 16.7 million display colors, anti-glare hard coating, analog RGB input, weight ranging 13 lbs to 24 lbs & 1280 x 1024 SXGA or 1600 x 1200 UXGA resolution. Applications include use for rack, wall, panel or kiosk installations in commercial, military & broadcast industries. One year limited warranty. RoHS compliant. Meet NEMA & Military Spec.

Optical and SEM (scanning electron microscopy) images of fabricated (a, b) CL and (c, d) CLSE pixel structures. The five white line patterns in (d) are the ITO interdigitated pixel and common electrodes. (e) Images from the normal direction and from 50 degrees to the left and right of a 2.3-inch-diagonal display incorporating the IPS TFT-LCD panel. (f) The three-black matrix (BM) patterns (top: BM covering both gate and data lines, middle: BM covering only the data lines, and bottom: without BM) and (g) optical images of pixels without BM (left: LC on and off voltages supplied to every other data line, right: LC off voltage supplied to all data lines).

Figure 3e shows images from the normal direction and from 50 degrees to the left and right of a 2.3-inch-diagonal display incorporating the IPS TFT-LCD panel fabricated in our laboratory, (f) the three black matrix (BM) patterns (top: BM covering both gate and data lines, middle: BM covering only the data lines, and bottom: without BM), and (g) optical images of panel areas without the BM (left: LC on and off voltages supplied to every other data line, right: LC off voltage supplied to all data lines). As can be seen in the image from the normal direction, the brightness and contrast of the display area with the top BM and middle BM patterns are almost the same, but the contrast of the display area without the BM is relatively lower because of the lower darkness level of the LC off pixels indicating “HITACHI”. As shown in Fig. 3g, this is due to light leaking through the aperture between the data line and adjacent common lines. Therefore, in the CL structure, the BM on the drain line is necessary to obtain a high contrast ratio by shielding light leakage. This is the same as in the conventional structure. On the contrary, there is no light leakage along the gate line through the gaps between the gate line and edges of the pixel/common electrodes, as is clearly shown in Fig. 3g. This is a unique advantage of the CL structure because the conventional structure must shield these gaps with the BM to prevent light leakage. The suppression of light leakage along the gate line in the CL structure is due to the driving scheme (see Fig. 2b,a for a comparison with the conventional structure). During the holding period (tOFF) in the conventional structure, regardless of the pixel voltage, Vp (including Vp = 0), nonzero Vgp and Vgc are always applied to keep the TFT off, and these voltages are applied to the LC layer, inducing light leakage as reported in

Figure 4a shows the gate voltage (Vg) dependence of the panel brightness, while the inset shows that of the TFT current (transfer characteristics). The gray curves are for the conventional IPS TFT-LCD with the TFT before enhancement, the common line, and the matrix BM (MBM) shown at the top of Fig. 3f. The blue curves are for the proposed CL structure with the enhanced TFT and the stripe BM (SBM) shown in the middle of Fig. 3f. In this case, enhanced TFT characteristics were obtained by using an MNOS TFT without back-channel oxidation that was enhanced by the BTS process. In both structures, the threshold voltages for panel brightness, defined by extrapolating the straight part of the brightness curves, reflect those of the TFT transfer curves defined as Vg at a drain current of 10−12 A, and they are well matched to be 4 V and 9 V, respectively. The maximum brightness for the CL structure is 137% higher than that for the conventional structure, which is due to the increase in the aperture ratio from 38 to 52% that results from the elimination of the common line and the BM covering the gate line.

(a) Dependence of panel brightness and TFT current on gate voltage for the conventional pixel structure of 38% aperture ratio (AR) with matrix black matrix (MBM) over both drain and gate lines and proposed CL pixel structure of 52% AR with strip black matrix (SBM) over only the drain lines. Transfer characteristics before and after bias temperature stress (BTS) treatment are shown in the inset. (b) Charging and (c) holding characteristics of enhanced TFT of the CL structure with gate as a common line. Vg and Vd in the TFT ON state are 30 V and +/−7 V, respectively.

To estimate the charging and holding characteristics of the MNOS-enhanced TFT in the panel, the gate TFT ON and OFF time dependences of the panel brightness were measured (Fig. 4b,c). The charging characteristics in Fig. 4b are plotted as a function of tON at tOFF = 16.6 ms, Vg = 30 V, and Vd = ± 7 V. The holding characteristics in Fig. 4c are plotted as a function of tOFF at tON = 34 μs. 95.1% charging at tON = 34 μs and 95.3% holding at tOFF = 16.6 ms indicate that the enhanced TFT has sufficient charging and holding performance to drive a standard VGA (640 × 480 pixels) panel (the number of scanning lines is estimated as tOFF/tON = 16.6/0.034 = 488).

To confirm the driving conditions for the CL structure without the BM along the gate line (with the SBM), the tOFF dependence of the contrast ratio (CR) in the CL panel was further investigated as shown in Fig. 5a, where CR is plotted as a function of tOFF for the CL panels with the matrix BM (MBM) and the strip BM (SBM). The inset shows the brightness in the bright (Vd = 7 V) and dark (Vd = 0 V) states of the CL panel with the SBM as a function of tOFF and an optical image of the panel with tOFF = 6.4 ms. The SBM and MBM panels keep CR higher than 240 with tOFF > 16.6 ms, the frame period of a display panel without flicker being noticeable to the human eye. both panels decrease CR when tOFF is less than 16.6 ms; the CR of the SBM panel decreases faster than the CR of the MBM panel. As shown in the inset, the decrease in CR was due to the increase in dark-state brightness with decreasing tOFF as light leakage increases along the gate line. This light leakage is induced by the voltage Vgp = Vgc = VgON = 30 V applied only for 34 μs during the TFT ON (charging) state, which is 1/488th the duration, tOFF = 16.6 ms, of the TFT OFF (holding) state with Vgp = Vgc = VgOFF = 0 V, but the ratio increases with decreasing tOFF and becomes effective enough to switch on LC layer and induce light leakage. However, it should be stressed again that the CL panel with the normal holding (TFT OFF) time of 16.6 ms does not suffer from the light leakage along the gate line, so the aperture ratio can be increased by removing the BM along the gate line.

Figure 6 indicates the effect of bias temperature stress (BTS) on the TFT characteristics. As the stressing time, tS, of the positive gate stress voltage, Vst =  + 77 V, increases from 0 to 3600 s, the transfer (Id-Vg) curve shifts in the positive direction (Fig. 6a). Vth is defined as Vg at which Id = 10−12 A and ΔVth is defined as the Vth shift from the initial value via BTS. As shown in Fig. 6b, ΔVth increases logarithmically with increasing tS: ΔVth = 2.17 + 4.93 × log (tS). The mechanism behind the gate-stress-induced Vth shift is electron tunnel injection from the a-Si:H semiconductor into the SiOx gate insulator. For confirmation, ΔVth of MNOS TFTs with different SiOx thicknesses is plotted as a function of the electric field applied to the SiOx layer in Fig. 6c. Here, the thickness of the SiOx was varied (5, 10, 20, 50 nm), while the SiN thickness was fixed at 200 nm. The electric field applied to SiOx, Eox, was calculated using the following equation,

Effect of bias temperature stress (BTS) on TFT characteristics. (a) The transfer (Id–Vg) curve shifts in the positive direction with positive gate bias stress of Vst =  + 77 V over the duration of 0–3600 s. (b) ΔVth, defined as the Vth shift from the initial value via BTS, increases logarithmically with increasing tS, following ΔVth = 2.17 + 4.93 × log (tS). (c) ΔVth of MNOS TFTs with different SiOx thicknesses from 5 to 50 nm as a function of the electric field applied to the SiOx layer.

Figure 7a shows the effect of back-channel oxidation (BCO) and passivation (PAS) on the Id-Vg characteristics of the MNOS TFT. The Id-Vg curve with Vth = 5.1 V is further enhanced to Vth = 10.9 V after BCO, although there is a slight degradation of the slope of the current increase in the sub-threshold region. The slope recovers after PAS without any change to the enhanced characteristics

(a) Effect of back-channel oxidation (BCO) and passivation (PAS) on Id–Vg characteristics of MNOS TFT. (b) Vth and Vth standard deviation, σVth, after BTS and after BCO without BTS treatments and (c) SiOX thickness as a function of position along gate-line, x.

The advantage of BCO over BTS is the uniformity of the enhanced characteristics; Fig. 7b shows the distribution of the enhanced Vth as a function of position along gate-line, x, for the MNOS TFTs connected with a 90-mm-long gate line in the TFT substrate after BTS and BCO treatments. The average value of Vth and the standard deviation, σVth, for pristine TFTs before BTS or BCO, are 5.1 V and 0.35 V, respectively. After BCO, Vth is uniformly enhanced, with an average Vth = 11 V and σVth = 0.4 V without increasing σVth. On the other hand, after BTS, Vth is nonuniformly enhanced with an average Vth = 9.3 V and σVth of 1.4 V. In particular, Vth increases linearly as a function of position along gate-line, x. As the gate SiOx thickness linearly decreases, from (54 nm) to (47 nm) with increasing x as shown in Fig. 7c, the increase in ΔVth after BTS with x is due to increase in the electric field applied to SiOx as shown in Fig. 6c and Eq. 1.

It has been shown that the Vth of the MNOS TFT is independent of the gate SiOx thickness when the thickness is more than 5 nm8a, Vth of the MNOS TFT with the BCO treatment becomes almost independent of the BCO SiOx thickness. As shown in the inset, the thickness of BCO SiOx composed of oxidized a-Si:H linearly increases with BCO processing time, and the Vth increase almost saturates at a BCO SiOx thickness greater than 5 nm. Therefore, the enhanced MNOS TFT after BCO has a uniformly high Vth that is robust to thickness fluctuations of the gate and BCO SiOx layers. BCO also has an advantage over BTS in terms of the stability of Vth as shown in Fig. 8b, which plots the annealing time dependence of Vth for BCO and BTS. In this experiment, the stoichiometry (x) of the gate SiOx was 1.78 for BTS and 1.78 and 1.9 for BCO. The annealing temperature in the N2 atmosphere was 200 °C. In the case of BTS, Vth decreased to the pristine value after approximately 5 h of annealing, while Vth decreased more slowly in the case of BCO. In particular, the annealing time required for Vth to fall to 7 V was 7.5 times longer than that of BTS. Increasing the stoichiometry (x) of the gate SiOx dramatically improved the BCO-enhanced Vth to as much as 11 V, which was stably maintained after 24 h of annealing at 200 °C.

(a) Dependence of Vth on thickness of back-channel oxidized (BCO) SiOX. The inset shows the SiOx thickness dependence on the BCO process time for RF powers of 200 W and 500 W. (b) Stability of Vth as a function of annealing time for three different TFTs with gate SiOx stoichiometry, x = 1.78 and bias temperature stress (BTS), x = 1.78 and BCO, and x = 1.9 and BCO. The temperature of annealing in the N2 atmosphere was 200 °C. (c) Band diagram of back-channel oxidized MNOS TFT. The red arrows show the electric dipoles at the SiOX/a-Si:H and a-Si:H/BCO SiOX interfaces.

A schematic band model for the MNOS TFT with the BCO treatment and the sectional structure of the interface between the a-Si:H and gate and BCO SiOx are shown in Fig. 8c. The uniformly high Vth that is independent of SiOx thickness is due to the dipoles generated at the channel and back-channel interfaces between a-Si:H and SiOx8 of reference

Regardless of which semiconductor is chosen for TFTs, there is one metric that is often considered to be the most important: the charge carrier mobility (µ). The mobility characterises how swiftly charge carriers can move through a given semiconductor and, although considered an intrinsic property, TFT-measured mobility is known to depend on various extrinsic factors. Mobility values vary wildly between materials families (Table 1) and in general, there is a typical TFT ‘mobility ethos’ of the bigger the number, the better the transistor, because the higher the carrier mobility, the more applications the TFT can be used for. This has not been good news for carbon-based organic semiconductors, which, for a long time, had mobility values that were a world away from their inorganic counterparts. But the same peculiar chemical nature that is responsible for their low mobilities also gives organic semiconductors extreme processing versatility, as well as unique mechanical properties, such as flexibility and stretchability. The latter qualities spawned the idea of a foldable, flexible electronics market that captured the imagination of people throughout the world. This enthusiasm for flexible, printed electronics has driven huge research efforts to improve the critically low mobilities of organic semiconductors, measured in organic TFTs (OTFTs).

Nevertheless, it is the high charge carrier mobility values for OTFTs that have been in the spotlight in recent years — for all the wrong reasons. In a haze of glory, excitement and misinterpretation, overestimated OTFT mobility values gradually started creeping into the literature circa 2004, until they were being published frequently at the peak of the mobility hype (2012–2017)2/Vs in the past 30 years

In this research thermal and fluid fields of a 32-inch commercial thin film transistor liquid crystal display (TFT-LCD) TV panel were investigated numerically and experimentally. The new trend in the production of TFT-LCD, TV panel is to have slimmer screen displays. The original design with 180 LEDs (light emitting diodes) placed at the top and bottom edges of the panels was modified. In the new design, the panels were illuminated using only 72 LEDs placed underside and inside the panels. By this modification an important cost reduction has been achieved alongside having slimmer screen displays. Heat dissipated by these 72 LEDs must be removed in order to assure good image quality and long service life. Hence an appropriate thermal management is indispensable. To analyze temperature distribution at steady state condition a CFD (computational fluid dynamics) computer code “FloEFD” was used. The results obtained from the computational analysis have been validated by using experimental techniques. For this purpose thermocouples were attached on the panel and after the steady state has been reached, temperatures have been recorded in order to compare them to the distribution obtained by “FloEFD”. Furthermore, a thermal camera image of the panel by FLIR Thermacam SC2000 test device was obtained as another validation for temperature distribution.

Sharp demonstrated a fourteen-inch TFT-LCD for TV in 1988 when the display size of the mass-produced TFT-LCD was three inches. The high display quality in Cathode Ray Tube size convinced other electronic companies to join the infant TFT-LCD industry aimed at emerging full-color portable PCs. Two decades later, TFT-LCDs replaced CRTs, making the vision of RCA"s LCD group in the 1960s a reality.

Sharp Technology Innovation Museum is located in the premise of Sharp Technology Center where LCD research was started and culminated in mass-producing the world-first mini-calculator mounted with LCD and C-MOS logic : the calculator is displayed at the British Science Museum.

It showed that an ideal display, namely, a flat, low-power, light-weight, CRT-sized full-color video display ,which could be used also in high ambient light, is technologically feasible, and that is exactly what had been long waited for to be used in an emerging information age since LCD was press-released in 1968 by RCA.

3. A large mother glass scheme could work for a-Si-TFT-LCD, which was proved by the high display uniformity across the entire display area. The mother glass 300mm x 320mm was the very forerunner of the mother glass generation competition which started around 1990, 2 years after Sharp 14-in. full color TFT-LCD was demonstrated.

At the very beginning of a-Si-TFT-LCD business startup, this work clearly showed a-Si-TFT-LCD have the potential to replace monster CRT in the coming information age by its superior characteristics: flatness, light-weight, small power consumption, high saturation full-color rendition, high readability in high ambient light, realized on the 14-in. display size, the most dominant size in the contemporary market by using the technology which was developed to mass-produce twenty 3-in. TFT-LCD TV panels laid out on the mother glass of 300mm x 320mm dimensions.

TV business group knew the market and joined the development project from the very beginning and gave a clear display quality target to TFT-LCD research group to achieve and make the TFT-LCD a viable display technology against CRT dominance.

[114] T. Nagayasu, T. Oketani, T. Hirobe, H. Kato, S. Mizushima, H. Take, K. Yano, M. Hijikigawa, and I. Washizuka, “A 14-in-diagonal full color a-Si TFT LCD,” in Proc. Int. Display Research Conf., San Diego, CA, Oct. 1988, pp. 56–58.

[9] G. H. Heilmeier, “Liquid crystal displays: An experiment in interdisciplinary research that worked,” IEEE Trans. Electron Devices, vol. ED-23, July 1976.

Sharp demonstrated a fourteen-inch TFT-LCD for TV in 1988 when the display size of the mass-produced TFT-LCD was three inches. The high display quality in Cathode Ray Tube size convinced other electronic companies to join the infant TFT-LCD industry aimed at emerging full-color portable PCs. Two decades later, TFT-LCDs replaced CRTs, making the vision of RCA"s LCD group in the 1960s a reality.

Describe briefly the intended site(s) of the milestone plaque(s). The intended site(s) must have a direct connection with the achievement (e.g. where developed, invented, tested, demonstrated, installed, or operated, etc.). A museum where a device or example of the technology is displayed, or the university where the inventor studied, are not, in themselves, sufficient connection for a milestone plaque.

Sharp Technology Innovation Museum is located in the premise of Sharp Technology Center where LCD research was started and culminated in mass-producing the world-first mini-calculator mounted with LCD and C-MOS logic : the calculator is displayed at the British Science Museum.

It showed that an ideal display, namely, a flat, low-power, light-weight, CRT-sized full-color video display ,which could be used also in high ambient light, is technologically feasible, and that is exactly what had been long waited for to be used in an emerging information age since LCD was press-released in 1968 by RCA.

3. A large mother glass scheme could work for a-Si-TFT-LCD, which was proved by the high display uniformity across the entire display area. The mother glass 300mm x 320mm was the very forerunner of the mother glass generation competition which started around 1990, 2 years after Sharp 14-in. full color TFT-LCD was demonstrated.

At the time when a mere small 3-in. a-Si-TFT-LCD production was just started with poor yield, unstable and far-from-being-matured production equipment, small output capacity drivers, engineers had to prepare line-defect free TFT-LCD panels with high display quality, meaning large contrast ratio, high color saturation with high uniformity, and they made a precise electrical and physical system analysis and designing and devised redundant pixel and bus line schemes, and employed normally-white LCD operation mode, which was first employed in 3-in. TFT-LCD panel, and developed the TFT-LCD panel and its driving scheme to achieve higher contrast ratio, better gray scale and full-color rendition, wider tolerance in temperature and cell-gap variations, leading higher display uniformity across the entire large display area, than normally-black mode could achieve in those days.

Sharp"s first application of TFT-LCD was television which is supposed to be exposed to "critical" consumers 3-5 hours everyday for more than 10 years.

So, from the very beginning of development project started in April 1984, TV business group, who understand the market, located in Yaita-shi, Tochigi-ken, and TFT-LCD research group located in Tenri-shi, Nara-ken, worked closely; even though, two places are about 600km apart.

TV group, headed by Magohiro ARAMOTO, whose leading member was Masakazu YAMAMOTO, joined by Shuhji KOHZAI later on, showed the clear target specifications and pointed out critical display quality factors to be improved, and also transferred TV evaluation methods to TFT-LCD research group; TFT-LCD research group, headed by Masataka MATUURA, whose leading members were Funada FUMIAKI, with Yutaka ISHII as sub-leader, for LC material and operation mode and acting deputy to Matsuura, Kohzo YANO for TFT process, Hiroshi TAKE for system designing of TFT, LCD panel and driving circuitry, and evaluation of TFT-LCD as an integrated system, achieved and acquired them.

In the production project started in November 1985, LCD business group, headed by Mitsuo ISHII, located in Yamato-Kohriyama-shi, Nara-ken, joined the project, bringing in panel production technology including large mother glass handling know-hows, and, the thin-film solar battery group, headed by Toshio TAKEMOTO, located in Shinjoh-shi, Nara-ken, was also incorporated into ISHII"s group,afterward, bringing in amorphous-Silicon(a-Si) thin-film solar-cell mass-production technology whose basics are similar to those of a-Si TFT.

In the Japanese Consumer Electronics Show, October 1986, the production project demonstrated 3-inch TFT-LCD TV which employed a normally-white LCD operation mode. The mechanical design of the 3-inch TFT-LCD module mounted on the demonstrated TV was done by Kenichi UKAI who joined the project June 1986 from Electronic Component Business Division, whose main products included miniaturized electronic TV tuners, located in Osaka-shi, Osaka-fu.

The world-first TFT-LCD factory with a large mother glass 300mmx320mm was build in the precinct of Research and Development Group, located in Tenri-shi, Nara-ken, toward the end of 1986, near the Central Reaearch Laboratories TFT-LCD research group belonged to.

April 1987, YANO and TAKE of TFT-LCD research group moved to LCD Business Division whose general manager was Isamu WASHIZUKA, to be the technology and engineering core members of the newly-created The 3rd Production Department which had all the essential functions to execute TFT-LCD business, such as TFT-LCD process engineering, electronics and mechanical engineerings, administration, and production, irregularly incorporated with Mitsuo ISHII as general manager.

The 1st Sharp LC-TV "3C-E1" with 3-inch TFT-LCD, display dot 384Hx240V in a triangle arrangement, was put on the martket June 1987, half a year later than originally scheduled; the TFT-LCD production yield was miserable, though.

In one of meetings held everyday in the evening to improve production yield of 3-inch TFT-LCD panel, Washizuka gave an additional mission to look into the future, and to search for TFT-LCD technology capability for TV, and instigated young engineers to study and propose larger display prototype development plans without giving any clear target size numbers and time frames.

Around middle of 1987, a voluntary project team was set up, headed by Mitsuo ISHII, whose leading members were Toshio AKAI for product planning, Kohzo YANO for TFT-LCD process and Hiroshi TAKE for electronics and system.

The project team almost reached a consensus to adopt 8.9-in. size for a challenging target: 6.6-in. seemed to give only a small impact; 14-in. seemed to be too risky to get good panels, meaning with high display uniformity across the entire display area, no-line defects and acceptable dot defects by infant technology and equipment.

TAKE made a phone call to Magohiro ARAMOTO, general manager of TV Division, and had guided the TFT-LCD development project to improve display quality for TV, to try to understand the TV market, and asked ARAMOTO what would be the minimum size of TFT-LCD to be widely used by people.

TAKE, evaluation and characterization research engineer by background, knew the difficulty to prepare 14-in. panel using the same process and equipment used to mass-produce 3-in. panels with poor yield, but decided to accept ARAMOTO’s number 14-in., saying to himself the possible largest size on the mother glass would show up, more clearly than smaller sizes, problems and issues TFT-LCD had to solve and tackle with to be a viable technology in TV and other markets dominated by CRTs.

The panel should be compatible with NTSC/M TV system, and display dot number was decided to be 642Hx480V with available analog driver-LSI output terminal numbers taken into consideration. The trios of red, green and blue primary color dots were arranged in a triangle pattern to maximize the resolution with the limited display dot number.

The target TFT-LCD panel specifications was accepted in the project team after YANO, with Hiroaki KATOH as his process designing section leader, made a thorough review of the TFT-LCD process and equipment in the 3-in.-mass-producing factory to make sure 14-in. was NOT impossible　, and authorized by WASHIZUKA afterwards.

The 14-in. TFT-LCD panels were prepared by using the production line whose main product was 3-inch TFT-LCD panel, and 4-inch TFT-LCD production was just started.

There were a lot of fierce arguments and misunderstandings within the newly-formed production department whoes members had been recruited from various departments of various business divisions of Sharp Corporation, but those were managed and solved by tightly sharing the common mission: Make TV displays for OUR TVs!: Sharp Corporation mass-produced B/W CRT-TV in 1953, 1st in Japan, under the license agreement with RCA, and had been one of the leading worldwide TV makers, but had not produced CRTs inhouse; all CRTs on Sharp TVs been bought from outside.

At the very beginning of a-Si-TFT-LCD business startup, this work clearly showed a-Si-TFT-LCD have the potential to replace monster CRT in the coming information age by its superior characteristics: flatness, light-weight, small power consumption, high saturation full-color rendition, high readability in high ambient light, realized on the 14-in. display size, the most dominant size in the contemporary market by using the technology which was developed to mass-produce twenty 3-in. TFT-LCD TV panels laid out on the mother glass of 300mm x 320mm dimensions.

TV business group knew the market and joined the development project from the very beginning and gave a clear display quality target to TFT-LCD research group to achieve and make the TFT-LCD a viable display technology against CRT dominance.

[114] T. Nagayasu, T. Oketani, T. Hirobe, H. Kato, S. Mizushima, H. Take, K. Yano, M. Hijikigawa, and I. Washizuka, “A 14-in-diagonal full color a-Si TFT LCD,” in Proc. Int. Display Research Conf., San Diego, CA, Oct. 1988, pp. 56–58.

[9] G. H. Heilmeier, “Liquid crystal displays: An experiment in interdisciplinary research that worked,” IEEE Trans. Electron Devices, vol. ED-23, July 1976.

[２] B.J.Lechner, "History Crystallized_A First-Person Account of the Development of Matrix-Addressed LCDs for television at RCA in the 1960s",Information Display 1/08 p26-30

Thin-film transistors are built by layering the thin films of an active semiconductor, hence the name, as well as a dielectric layer and some metallic contacts on a glass substrate. Glass is used because it is nonconductive with excellent optical clarity; it is also nonreactive to the chemicals used in semiconductor processing. In contrast, in the construction of a typical transistor, the substrate used is a semiconductor material, usually a silicon wafer.

Thin-film transistors are primarily used in LCD displays, which is why glass is used as the substrate. TFT technology is also used in both direct and indirect capture digital radiography detectors used in medical radiography. Active-matrix organic light-emitting diode (AMOLED) screens also have a TFT layer.

A TFT is a type of transistor used in active-matrix LCD screens. TFT LCD screens use a separate transistor to control each pixel in the display. They allow the electrical current that controls each pixel to turn on and off quickly, which decreases response time and makes on-screen motion smoother. TFT LCDs are often used as computer monitors, televisions, mobile phone screens, and other flat-panel color displays.

The name "Thin Film Transistor" is derived from the manufacturing process. The manufacturer first applies thin films of a semiconductor (like amorphous silicon) and dielectric materials to a flat, non-conductive surface (like glass). Unneeded silicon is etched away, leaving only a grid of transistors and the transparent glass surface. These transistor panels are thin enough to fit between a polarized backlight and the layer of liquid crystals. These transistors apply an electrical current to the liquid crystals, altering their arrangement to block light in certain ways. The light then passes through other layers of the screen, including a color filter and polarized light filter, to display the final image.

Not all TFT LCD screens are made the same. There are several types of TFT panels, made by distinct methods, and with different performance characteristics. The two most common types are TN and IPS.

Twisted Nematic (TN) panels contain liquid crystals that twist as an electric current is applied. As the crystals twist, they allow varying amounts of polarized light to pass through. TN panels are the easiest type of TFT LCD to produce and offer the quickest response times. However, TN panels don"t display colors as accurately as other types of panels, particularly when viewed at an angle.

MKS TFT32 is an independent color touch product developed for maker base , which is suitable for open source 3D printers. It can be used in a series of motherboards such as MKS Base, MKS Gen, MKS Sbase and so on.