Effect of a-SiNx:H composition on band bending near the interface of a-Si:H/a-SiNx:H layered structures

The effect of band bending near the interface of a-Si:H/a-SiNx:H layered structures has been investigated for various a-SiNx:H compositions by measuring in-plane dark current and photocurrent. The dark current of a-Si:H/a-SiNx:H layered structures increases about four orders of magnitude and the activation energy decreases with a decrease in x of a-SiNx:H. The photocurrent also increases about four orders of magnitude with a decrease in x. This photocurrent enhancement is larger in the shorter wavelength region, and this spectral change agrees with the photocurrent spectral change induced by an increase in gate bias in thin-film transistor structures. From these results it is found that the band bending toward electron accumulation in a-Si:H near the a-Si:H/a-SiNx:H interface increases with a decrease in x of a-SiNx:H, resulting in high photoconductivity.