Effects of hydrogenation on the performance and stability of p-channel polycrystalline silicon thin-film transistors

The effects of hydrogenation on the performance and stability under electrical stress of p-channel poly crystalline silicon thin-film transistors (polysilicon TFTs) are investigated, The hydrogenation is performed in pure H-2 plasma or in plasma of 4%, H-2 diluted in He gas. Devices hydrogenated in plasma of H-2/He exhibit Iower subthreshold swing with better uniformity and lower leakage current. which indicate passivation of mid-gap trap states arising from dangling bonds at the grain boundaries. Hot-carrier experiments demonstrate that the stability of p-channel TFTs is improved as the hydrogenation becomes more efficient due to the effective removal of donor-type trap states at the grain boundaries. (C) 2003 Elsevier Science Ltd. All rights reserved.