79:(LCD) flat panels because they can be assembled into complex high-current driver circuits. Amorphous Si-TFT electrodes drive the alignment of crystals in LCDs. The evolution of LTPS-TFTs can have many benefits such as higher device resolution, lower synthesis temperature, and reduced price of essential substrates. However, LTPS-TFTs also have several drawbacks. For example, the area of TFTs in traditional a-Si devices is large, resulting in a small aperture ratio (the amount of area which is not blocked by the opaque TFT and thus admits light). The incompatibility of different aperture ratios prevents LTPS-based complex circuits and drivers from being integrated into a-Si material. Additionally, the quality of LTPS decreases over time due to an increase in temperature upon turning on the transistor, which degrades the film by breaking the Si-H bonds in the material. This would cause the device to suffer from drain breakdown and current leakage, most notably in small and thin transistors, which dissipate heat poorly.
58:(a-Si) is an excellent precursor for forming p-Si films with stable structures and low surface roughness. Silicon film is synthesized by low-pressure chemical vapor deposition (LPCVD) to minimize surface roughness. First, amorphous silicon is deposited at 560–640 °C. Then it is thermally annealed (recrystallized) at 950–1000 °C. Starting with the amorphous film, rather than directly depositing crystals, produces a product with a superior structure and a desired smoothness. In 1988, researchers discovered that further lowering the temperature during annealing, together with advanced plasma-enhanced chemical vapor deposition (PECVD), could facilitate even higher degrees of conductivity. These techniques have profoundly impacted the microelectronics, photovoltaic, and display enhancement industries.
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Apart from the improvement of the TFTs themselves, the successful application of LTPS to graphic display also depends on innovative circuits. One recent technique involves a pixel circuit in which the outgoing current from the transistor is independent of the threshold voltage, thus producing uniform
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TFT, a capacitor, and a control element to control the image resolution. Enhancing the performance and microlithography for TFTs is important for advancing LTPS active-matrix OLEDs. These many important techniques have allowed the mobility of crystalline film to reach up to 13 cm2/Vs, and they
117:
XeCl-ELA succeeds in crystallizing a-Si (thickness ranges from 500-10000Å) into p-Si without heating the substrates. The polycrystalline form has larger grains that yield better mobility for TFTs due to reduced scattering from grain boundaries. This technique leads to the successful integration of
601:
Tai, Y.-H., B.-T. Chen, Y.-J. Kuo, C.-C. Tsai, K.-Y. Chiang, Y.-J. Wei, and H.-C. Cheng. "A New Pixel
Circuit for Driving Organic Light-Emitting Diode With Low Temperature Polycrystalline Silicon Thin-Film Transistors." Journal of Display Technology 01.01 (2015): 100-104. IEEE Xplore. Web. 2 Mar.
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of the screen based on the content being displayed. This means that the screen can operate at a low refresh rate when displaying static images or text, but can ramp up to a higher refresh rate when displaying dynamic content like videos or games. LTPO displays are known for their improved battery
588:
Banger, K. K., Y. Yamashita, K. Mori, R. L. Peterson, T. Leedham, J. Rickard, and H. Sirringhaus. "Low-temperature, High-performance
Solution-processed Metal Oxide Thin-film Transistors Formed by a ‘sol–gel on Chip’ Process." Nature Materials (2010): 45–50. Nature Materials. Web. 2 Mar.
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Inoue, Satoshi, Hiroyuki
Ohshima, and Tatsuya Shimoda. "Analysis of Degradation Phenomenon Caused by Self-Heating in Low-Temperature-Processed Polycrystalline Silicon Thin Film Transistors." Japanese Journal of Applied Physics 41 (2002): 6313-319. IOP Sciences. Web. 2 Mar.
142:(OLED) displays because it has high resolution and accommodation for large panels. However, variations in LTPS structure would result in non-uniform threshold voltage for signals and non-uniform brightness using traditional circuits. The new pixel circuit includes four
385:
Zhiguo, Meng, Mingxiang Wang, and Man Wong. "High
Performance Low Temperature Metal-Induced Unilaterally Crystallized Polycrystalline Silicon Thin Film Transistors for System-on-Panel Application." IEEE Transactions On Electron Devices 47.02 (2000).
70:
Diagram of liquid-crystal display. When current is applied to the transistor, the liquid crystals become aligned and no longer rotate the incident polarized light. This results in no transmission through the second polarizer, creating a dark
362:
Hatalis, Miltiadis K., and David W. Greve. "Large Grain
Polycrystalline Silicon By Low-Temperature Annealing Of Low-Pressure Chemical Vapor Deposited Amorphous Silicon Films." Applied Physics 63.07 (1988): 2266.
579:
Uchikoga, Shuichi. "Low-Temperature
Polycrystalline Silicon Thin-Film Transistor Technologies for System-on-Glass Displays." MRS Bulletin (2002): 881-86. Google Scholar. MRS Bulletin. Web. 2 Mar. 2015.
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Harbeke, G., L. Krausbauer, E.F. Steigmerier, and A.E. Widmer. "Growth and
Physical Properties of LPCVD Polycrystalline Silicon Films." Journal of the Electrochemical Society (1984): 675. Print.
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Sameshima, T., S. Usui, and M. Sekiya. "XeClExcimer Laser
Annealing Used in the Fabrication of Poly-Si TFT's." IEEE Electron Device Letters 07.05 (1986): 276-78. IEEE Xplore. Web. 2 Mar. 2015.
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G. A. Bhat, Z. Jin, H. S. Kwok, and M. Wong, “Effect of MIC/MILC Interface On The
Performance Of MILC-TFT’s,” in Dig. 56th Annu. Device Research Conf., June 22–24, 1998, pp. 110–111.
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irradiation. The counterpart of a-Si, polycrystalline silicon, which can be synthesized from amorphous silicon by certain procedures, has several advantages over widely used a-Si TFT:
453:
Kuo, Yue. "Thin Film
Transistor Technology—Past, Present, and Future." The Electrochemical Society Interface (2013). Electrochemical Society Interface. Web. 1 Mar. 2015.
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Fonash, Stephen. "Low Temperature Crystallization and Patterning of Amorphous Silicon Film On Electrically Insulating Substrates." United States Patent (1994). Print.
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industries, since the use of large glass panels prohibits exposure to deformative high temperatures. More specifically, the use of polycrystalline silicon in
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that has been synthesized at relatively low temperatures (~650 °C and lower) compared to traditional methods (above 900 °C). LTPS is important for
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While amorphous silicon lacks crystal structure, polycrystalline silicon consists of various crystallites or grains, each of which has an organized lattice.
255:, or IGZO). In LTPO, the switching circuits use LTPS while the driving TFTs use IGZO materials. LTPO allows for more efficient use of power by
477:"Extraction of trap states in laser-crystallized polycrystalline-silicon thin-film transistors and analysis of degradation by self-heating"
372:
Hatalis, M.K., and D.W. Greve. "High-Performance Thin-Film Transistors In Low-Temperature Crystallized LPCVD Amorphous Silicon Films."
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Polycrystalline silicon (p-Si) is a pure and conductive form of the element composed of many crystallites, or grains of highly ordered
475:
Kimura, Mutsumi; Inoue, Satoshi; Shimoda, Tatsuya; Tam, Simon W.-B.; Lui, Basil; Migliorato, Piero; Nozawa, Ryoichi (2002-03-15).
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Kimura, Mutsumi; Inoue, Satoshi; Shimoda, Tatsuya; Lui, Basil; French, William; Kamohara, Itaru; Migliorato, Piero (2001).
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703:
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555:"Development of poly-Si TFT models for device simulation: In-plane trap model and thermionic emission model"
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XeCl Excimer-Laser Annealing (ELA) is the first key method to produce p-Si by melting a-Si material through
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516:"Method for the determination of bulk and interface density of states in thin-film transistors"
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38:(LTPS-TFT) has high potential for large-scale production of electronic devices like flat panel
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panels using a combination of LTPS TFTs and hybrid-oxide and polycrystalline silicon (HOP).
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Lui, Basil; Quinn, M.J.; Tam, S.W.-B.; Brown, T.M.; Migliorato, P.; Ohshima, H. (1998).
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408:"Investigation of the low field leakage current mechanism in polysilicon TFT's"
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have helped to mass-produce LEDs and LCDs over 500 ppi in resolution.
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SID Conference Record of the International Display Research Conference
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Lui, Basil; Tam, S. W.-B.; Migliorato, P.; Shimoda, T. (2001-06-01).
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247:) is a type of OLED display backplane technology developed by
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639:"What is LTPO? How this tech delivers killer phone displays"
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Although the core technology in LTPO is developed by Apple,
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brightness. LTPS-TFT is commonly used to drive organic
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Transistor type used in the flat-panel display industry
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614:"LTPO backplane technology - introduction and news"
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133:Schematic of LTPS-TFT being used to drive an OLED
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75:Amorphous silicon TFTs have been widely used in
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275:also has its proprietary technology for LTPO
251:that combines both LTPS TFTs and oxide TFTs (
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663:"Samsung Display's LTPO tech is called HOP"
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113:Available for high integration of circuits.
667:THE ELEC, Korea Electronics Industry Media
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20:Low-temperature polycrystalline silicon
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257:dynamically adjusting the refresh rate
118:complicated circuits in LCD displays.
46:Development of polycrystalline silicon
412:IEEE Transactions on Electron Devices
241:Low-temperature polycrystalline oxide
637:Moore-Colyer, Roland (2021-04-02).
110:High resolution and aperture ratio;
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125:Development of LTPS-TFT devices
54:. In 1984, studies showed that
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260:life and can be found in some
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83:Processing by laser annealing
62:Use in liquid-crystal display
374:IEEE Electron Device Letters
268:, and other mobile devices.
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612:Mertens, Ron (2019-02-10).
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42:displays or image sensors.
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520:Journal of Applied Physics
481:Journal of Applied Physics
694:Electronics manufacturing
376:08 (1987): 361–64. Print.
295:Indium gallium zinc oxide
253:indium gallium zinc oxide
561:(in Japanese): 423–426.
704:Group IV semiconductors
699:Liquid crystal displays
320:Polycrystalline silicon
310:Monocrystalline silicon
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28:polycrystalline silicon
305:Liquid-crystal display
190:Deposition Temperature
168:Mobility (cm^2 /(V*s))
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77:liquid-crystal display
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719:Allotropes of silicon
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36:thin-film transistors
300:Light-emitting diode
140:light-emitting diode
714:Silicon solar cells
325:Wafer (electronics)
163:Polycrystalline Si
229:Relatively higher
201:Driver Integration
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73:
532:10.1063/1.1361244
526:(11): 6453–6458.
493:10.1063/1.1446238
424:10.1109/16.658833
290:Amorphous silicon
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179:Deposition Method
105:electron mobility
56:amorphous silicon
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266:smartwatches
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218:>500 ppi
204:Only partial
196:600 °C
160:Amorphous Si
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643:Tom's Guide
262:smartphones
193:350 °C
688:Categories
673:2023-02-24
648:2023-02-24
623:2023-02-24
332:References
212:Resolution
146:TFTs, one
618:OLED Info
567:1083-1312
540:0021-8979
501:0021-8979
432:1557-9646
709:Crystals
283:See also
174:>500
273:Samsung
32:display
565:
538:
499:
430:
386:Print.
363:Print.
277:AMOLED
148:p-type
144:n-type
71:pixel.
602:2015.
589:2015.
396:2015.
249:Apple
182:PECVD
107:rate;
103:High
97:laser
26:) is
563:ISSN
536:ISSN
497:ISSN
428:ISSN
245:LTPO
236:LTPO
223:Cost
185:ELA
24:LTPS
528:doi
489:doi
420:doi
226:Low
215:Low
171:0.5
40:LCD
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Text is available under the Creative Commons Attribution-ShareAlike License. Additional terms may apply.
