Temperature and Electron Concentration Dependences of 1/f Noise in Hg$_{1-x}$Cd$_x$Te -- Evidence for a Mobility Fluctuations Mechanism

TL;DR

This study examines the 1/f noise in HgCdTe materials and FETs, revealing weak temperature and electron concentration dependence, suggesting mobility fluctuations as the primary noise mechanism, similar to graphene.

Contribution

It provides new evidence that mobility fluctuations dominate 1/f noise in HgCdTe, supported by experimental data across different structures and conditions.

Findings

Weak temperature dependence of 1/f noise

Weak electron concentration dependence of 1/f noise

Mobility fluctuations identified as the dominant noise mechanism

Abstract

Hg$_{1-x}$Cd$_x$Te is a unique material with the band-gap tunable by the temperature, pressure, and cadmium content in a wide range, from 1.6 eV to inverted band-gap of -0.3 eV. This makes Hg$_{1-x}$Cd$_x$Te one of the key materials for infrared and terahertz detectors, whose characteristics largely depend on the material noise properties. In this work, we investigated the low-frequency 1/f noise in a thick (800 nm) HgCdTe layer and in a field effect transistor (FET) with an 8 nm wide HgTe quantum well. Both structures exhibited a small contribution from contact noise and showed weak noise dependences on temperature. Investigation of the 1/f noise in HgTe quantum well FET as a function of gate voltage revealed that the noise also depends weakly on electron concentration. These findings indicate that the noise properties of Hg$_{1-x}$Cd$_x$Te are similar to those of graphene, where mobility fluctuations were found to be the dominant mechanism of the 1/f noise.