Calculations of High-Frequency Noise Spectral Density of Different CdTe Metal–Semiconductor–Metal Schottky Contacts

Abstract

An analytical approach for the study of high-frequency noise in different CdTe Schottky contacts is proposed. The model takes into account the fluctuations from three primary current sources: the leakage current through the Schottky barrier, the fluctuations of surface charge current, and the excess carrier density produced by light illumination (photocurrent). In particular, the current densities related to the perturbation of the electric field inside the whole structure and the free carrier fluctuations are used to determine the detectivity in the Giga and the Terahertz frequencies. It is shown that the current spectral density exhibits a resonance peak near 109 Hz due to the free carrier concentration. The excess carrier fluctuations show a negligible contribution to the total spectral current density. It was found that the Au-S-Au structure presents a high detectivity due to their low noise level of the leakage current. These findings and the detailed model describing the current fluctuation processes in the detector is crucial for the development of detection technology.