1/f noise and specific detectivity of HgCdTe photodiodes passivated with ZnS-CdS films

Abstract

1/f noise in HgCdTe photodiodes has been measured as a function of temperature, diode bias, and dark current. The dependence of 1/f noise on dark current was measured over a wide temperature range. At low temperatures, where surface generation and leakage current were predominant, a linear relationship between 1/f noise and dark current was observed. At higher temperatures, where diffusion current is predominant, the correlation no longer holds. The temperature dependence of 1/f noise was also determined. The temperature dependence of the 1/f noise was found to be the same as that for the surface generation and leakage currents. All the data obtained in these experiments could be fit with theoretical predictions by a simple relationship between 1/f noise and dark current. The 1/f noise in the HgCdTe photodiode varies with diode bias, temperature, and dark current only through the dependence of the surface current on these devices. The maximum specific detectivity (D*) value and the maximum signal-to noise ratio are approximately 3.51/spl times/10/sup 10/ cm/spl middot/Hz/sup 1/2//W and 5096 at 50 mV reverse bias, respectively.