Channel Film Thickness Effect of Low-Temperature Polycrystalline-Silicon Thin-Film Transistors

In this paper, the channel-film-thickness effect of low-temperature polycrystalline-Si thin-film transistors (LTPS-TFTs) is investigated. Greater channel film thickness can provide a higher field-effect mobility μ
_FE
, rising from 14.33 to 22.33 cm
²
/ V.s, as the channel film thickness increases from 55 to 120 nm, due to grain-size effect. In addition, varying the channel film thickness of LTPS-TFTs results in different junction leakage current due to the source/drain (S/D) junction area effect. Moreover, the S/D series resistance also significantly increases when the channel film thickness is reduced from 120 to 35 nm, leading to poor field-effect mobility _FE and driving current. Consequently, the optimum channel film thickness for active-matrix liquid-crystal displays may be identified.