1/f Noise in (Hg, Cd)Te photodiodes

In this article we present results of experiments to characterize 1/ f noise in Hg 0.7 Cd 0.3 Te n ⁺ -on-p junction photodiodes. Under zero-bias voltage conditions, the photodiodes display no 1/ f noise, even in the presence of large photocurrents. Under reverse-bias voltage operation, 1/ f noise is observed. In these experiments, the 1/ f noise was measured as a function of temperature, diode bias voltage, and photon flux. Since these parameters varied the relative contributions of the various current mechanisms, the diode current mechanism responsible for 1/ f noise was isolated. It was found that 1/ f noise is independent of photocurrent and diffusion current but is linearly related to surface generation current. It is proposed that 1/ f noise in reverse-biased (Hg, Cd)Te photodiodes is a result of modulation of the surface generation current by fluctuations in the surface potential.