13.3: A Novel a‐Si TFT Pixel Circuit with High Immunity to the Degradation of the TFTs and OLEDs Used in AMOLED Displays

Lu, Hau Yan; Liu, Po–Tsun; Hu, Chia-Lin; Chang, Ting Chang; Chi, Sien

doi:10.1889/1.2785255

Cited by 2 publications

(1 citation statement)

References 7 publications

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“…The poly-Si crystallized by laser annealing has been widely used in AM-OLED and AM-LCD [1,2]. Excimer laser has been commonly applied in the low temperature poly Silicon TFT fabrication process, but it is limited by itself high cost [3,4].…”

Section: Introductionmentioning

confidence: 99%

The influence of Si precursor on poly‐Si crystallized by YAG laser

Yao

Wang

et al. 2010

Phys. Status Solidi (c)

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The influence of the Si-based crystallization precursor on the quality of the resulted poly-Si crystallized by 2ω YAG laser was investigated in this paper. Based on the simulation analysis, we suggested that the H content in crystallization precursor maybe one of main effect factors. It has been found that the lower H content in Si-based precursor, the better crystallinity of the resulted poly-Si is. By using the low H content Si-based film as the precursor, the poly Silicon with the grain size of about 500 nm crystallized by 2ω YAG was obtained at the relatively optimal crystallization conditions. Meanwhile, a dehydrogenation process before laser crystallization also could be omitted. It would be beneficial to lower cost of crystallization of a-Si.

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Section: Introductionmentioning

confidence: 99%

The influence of Si precursor on poly‐Si crystallized by YAG laser

Yao

Wang

et al. 2010

Phys. Status Solidi (c)

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Crystallization of μc-Si on plastic substrate by using a pulsed double-frequency YAG laser

Meng

et al. 2008

Optoelectron. Lett.

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Thin film transistors (TFTs) of microcrystalline silicon ( c-Si) can provide higher mobility and stability than that of a-Si and better uniformity than that of poly-Si TFTs, and it would be more suitable to be applied to larger-area AMOLEDs. By using 2 YAG laser annealing, crystalline c-Si thin film on plastic substrate has been investigated and the proper laser energy needed for crystallization has been indicated. It has been found that the dehydrogenation process at 300-450 o C for a few of hours could be omitted by decreasing the H content in the crystallization precursor, which is suitable for laser crystallization on plastic substrates. The crystalline volume fraction (X ( ( c) and the grain size of the resulted X X c-Si could be adjusted by controlling the laser energy. By this method, the c-Si on plastic substrate with Xc and grain size is respectively 85% (at the maximum) and 50 nm.Low-temperature polycrystalline silicon (LTPS) and amorphous silicon (a-Si) based TFTs have been used as activematrix organic light-emitting diode (AMOLED) display [1][2] . Unfortunately, both of the above silicon-based TFTs have shown their drawbacks. The a-Si TFTs suffer from the low mobility and bad reliability, and their threshold voltage degradation at gate-bias stress is one of the most serious problems. Polycrystalline silicon (poly-Si) based TFTs show higher performances, but which are limited by the high cost and discrete of TFT characteristics over a large areas. Another approach is the micro-crystalline silicon ( c-Si) TFT. The design concepts of TFT for OLED include starting from aSi, reducing V th comparable to LTPS, and improving electron mobility by an order of magnitude [3] . It has been reported that electron mobility around 5-10 Vs/cm 2 would be enough to drive OLED [4][5] . This indicates that microcrystalline Si can be used as an alternative material for active layer in TFT because of its higher mobility (by one order of magnitude) and better stability under the bias stress than that of a-Si. Many works have been reported and various ideas to get microcrystalline silicon were proposed. PECVD is commonly used to directly deposit c-Si [6][7] . By this method, though the process is relatively simple and the substrate temperature can be lower than 250 , the structure of c-Si deposited by PECVD is incompact due to its column-growth structure as shown in Fig.1 [7] . There are many cavities between the column grains, which might be contributed by the etching effect of H o or H + during the c-Si deposition. These cavities might make oxygen easily penetrate into the material and result in high dark conductivity, because of the oxygen atoms as donors in Si-Si network. The drawback of too high dark conductivity of c-Si could degrade the modulating effect of TFT by gate voltage, which has been verified in our previous work [7] . In this paper, the crystallization of cSi using 2 YAG laser on plastic substrate has been investigated. The laser-crystallized c-Si has a more compact structure and a more smooth morphology than...

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13.3: A Novel a‐Si TFT Pixel Circuit with High Immunity to the Degradation of the TFTs and OLEDs Used in AMOLED Displays

Cited by 2 publications

References 7 publications

The influence of Si precursor on poly‐Si crystallized by YAG laser

The influence of Si precursor on poly‐Si crystallized by YAG laser

Crystallization of μc-Si on plastic substrate by using a pulsed double-frequency YAG laser

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