Investigations into the source of 1/f noise in HgxCd1−xTe diodes

This work is aimed at elucidating the mechanism of 1/f noise in Hg_xCd_1−xTe diodes in order to reduce 1/f noise in high-performance thermal cameras. Currently, to reach the required signal-to-noise ratio, the operating temperature of thermal cameras is 77 K. If 1/f noise could be reduced, this operating temperature could be raised without reducing the signal-to-noise ratio, allowing cheaper, smaller, and lighter cooling systems to be used. There are still some fundamental aspects of 1/f noise that are not fully understood. One aspect in particular is whether the noise is caused by mobility or number density fluctuations because both could give the conductivity fluctuations observed. This paper explores the noise coupling and current coupling between diodes on an array. It is shown that 1/f noise is present on the photons emitted from a forward-biased diode, suggesting that the rate of radiative recombination fluctuates. The results suggest that these fluctuations are due to carrier number-density fluctuations. From correlation measurements, it is shown that at least 32% of the 1/f noise in the forward-biased diode is correlated with carrier density fluctuations in Hg_xCd_1−xTe diodes.