Effect of Cl incorporation on the performance of amorphous silicon thin film transistors

We have studied the effect of Cl incorporation on the performance of amorphous silicon thin film transistors (a-Si:H(:Cl) TFTs). The off-state leakage current of a-Si:H(:Cl) TFTs under light illumination is much lower than that of a-Si:H TFTs, because the photoconductivity of a-Si:H(:Cl) is much lower than that of conventional a-Si:H. The a-Si:H(:Cl) films deposited between [SiH2Cl2]/[SiH4]=0.04 and [SiH2Cl2]/[SiH4]=0.12 show p-type conduction, leading to the much lower photoconductivity. The TFT using a-Si:H(:Cl) deposited with [SiH2Cl2]/[SiH4]=0.04 exhibits a field effect mobility of 0.41 cm2/V s and a threshold voltage of 5.56 V; however the off-state leakage current under light illumination is two orders of magnitude smaller than that of a conventional a-Si:H TFT.