H在a-SiN_x:H光电导衰减中的作用

The Effect of H on the Photoconductivity Degradation of a-SiN_x:H

在真空蒸发硅的同时，分别用N离子和NH3离子轰击生长表面，获得具有不同H和N含量的a－SiNx和a－SiNx：H薄膜。对于这些薄膜，只要它们具有光电导特性，就可以观察到光电导衰减现象。实验分析表明，H在光电导衰减中不起直接作用，而是通过增大a－SiNx：H的光学能隙，使陷阱更为有效；以及减少Si≡Si－复合中心，从而有可能提高非平衡自由或流子密度和增强电荷被陷的速率，而间接地增强光电导衰减。

We use N and NH3 ion beam assited vacuum evaporation to deposite a-SiNx and a-SiNx:H films,respectively. The resulting films contain different H and N concentration. As long as these films are photoconducting,they appear photoconductivity degradation. The experiment shows that H does not play direct role in the degradation. However,H can increase the optical gap of a-SiNx,which makes trapping more effective. It can also reduce the density of the recombination centers of Si≡Si- dangling bonds,which would increase the excess carrier density and the rate of charge trapping. Boh of them speed the photoconductivity degradation.