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.