Investigation of silicon grain structure and electrical characteristics of TFTs fabricated using different crystallized silicon films by atmospheric pressure micro-thermal-plasma-jet irradiation

Amorphous silicon (a-Si) films were crystallized using three grain growth modes induced by micro-thermal-plasma-jet (mu-TPJ) irradiation and applied to the channel regions of thin-film transistors (TFTs). Solid phase crystallization (SPC) formed microcrystalline grains and showed a lower crystallinity of 70%, whereas leading wave crystallization (LWC) and high-speed lateral crystallization (HSLC) formed significantly larger grains than the TFT channel region. The SPC-TFT showed a lower field-effect mobility (mu(FE)) due to the small grain size and the existence of many grain boundaries, whereas LWC- and HSLC-TFT channels were formed by only single grains and showed a mu(FE) higher than 300cm(2)V(-1)s(-1) in the n-channel. The defect density of HSLC was smaller than that of LWC; consequently, the HSLC-TFT performed better than the LWC-TFT. The maximum mu(FE) values of n-and p-channel HSLC-TFTs were 418 and 224cm(2)V(-1)s(-1), respectively. (C) 2014 The Japan Society of Applied Physics