Noise Spectra of SIU-GaAs Pad Detectors With Guard Rings

TL;DR

This study characterizes the current noise spectra of SIU-GaAs pad detectors with guard rings, revealing excess noise components, dielectric relaxation effects, and deviations from shot noise expectations.

Contribution

It provides detailed noise spectra analysis of SIU-GaAs Schottky diodes with guard rings, including effects of bias and frequency, which was previously unexplored.

Findings

Excess noise component with low frequency corner below 1kHz

White noise magnitude is about half of shot noise prediction

Noise reduction observed at 20kHz due to dielectric relaxation

Abstract

This paper presents current noise characterization of circular pad Schottky barrier diodes with guard rings. The diodes were fabricated from undopped semi-insulating GaAs, SIU-GaAs, at the University of Glasgow. Current noise spectra were obtained for the detectors for two pad sizes, with reverse bias applied. Three measurements were also made on one of the detectors under forward bias. The noise spectra show an excess noise component, with a low frequency corner at less than 1kHz, and a flat region at higher frequencies. The magnitude of the white noise is approximately half that expected from shot noise theory for the given leakage currents. A fall in the magnitude of the noise was observed at 20kHz which is attributed to the dielectric relaxation time of the material.