1/fnoise in amorphous siliconnipandpindiodes

In this article noise measurements on amorphous silicon nip and pin diodes are presented and discussed with regard to standard models for flicker noise. It is shown that 1/f noise is present in the dark forward current of a-Si:H diodes as well as in the photocurrent at low forward or reverse bias. The dependence of the noise power spectral density on dark current and photocurrent density, diode area, thickness, and current aging leads us to the conclusion that fluctuations in the electron injection current at the n+ contact are the reason for 1/f noise. This model is further supported by the current and frequency dependence of the shot noise in the photocurrent. We assume that the trapping of carriers switches on and off current filaments in the diode interface layer.