Double-Crystalline Silicon Channel Thin Film Transistors Fabricated Using Continuous-Wave Green Laser for Large Organic Light-Emitting Diode Displays

Abstract

We developed double-crystalline silicon channel thin film transistors (TFTs) whose active region consisted of a polysilicon layer and a microcrystalline silicon layer. The polysilicon layer was formed by continuous-wave green laser annealing with scalability to large substrates. The microcrystalline silicon layer formed on the polysilicon layer provides a sufficient channel etching margin for the fabrication of TFTs on large substrates without degradation of TFT mobility. The kink-free output characteristics were realized by a band-gap engineering method using a microcrystalline silicon layer. The TFT characteristics desirable for organic light-emitting diode display applications, namely, high mobility, high reliability, and kink-free output characteristics, have been successfully demonstrated.

Remarkable Improvement in Foldability of Poly‐Si Thin‐Film Transistor on Polyimide Substrate Using Blue Laser Crystallization of Amorphous Si and Comparison with Conventional Poly‐Si Thin‐Film Transistor Used for Foldable Displays

“…[24][25][26][27][28][29] In contrast, low-temperature poly-Si (LTPS) TFT backplanes on polyimide (PI) substrate have high mobility and excellent stability so that current foldable and flexible AMOLED displays are using excimer laser annealing (ELA) poly-Si TFT backplanes on PI substrates. [30][31][32][33][34][35][36][37][38][39][40][41] The crystallization of amorphous silicon (a-Si) on glass substrate can be possible by using solid phase crystallization (SPC), [42][43][44] metal-induced crystallization (MIC), [45][46][47] ELA, [48][49][50][51] and continuous wave (CW) [52][53][54][55][56][57][58][59][60][61][62][63] laser annealing. Because of no intradefects in the grains, the ELA poly-Si is widely used for the manufacturing of AMOLED and active-matrix liquid crystal display (AMLCD).…”

“…The crystallization of amorphous silicon (a‐Si) on glass substrate can be possible by using solid phase crystallization (SPC), metal‐induced crystallization (MIC), ELA, and continuous wave (CW) laser annealing. Because of no intradefects in the grains, the ELA poly‐Si is widely used for the manufacturing of AMOLED and active‐matrix liquid crystal display (AMLCD) .…”