Characterization of Chromium Compensated GaAs as an x-ray Sensor Material for Charge-Integrating Pixel Array Detectors

TL;DR

This study characterizes chromium compensated GaAs as an x-ray sensor for charge-integrating pixel detectors, examining how temperature, bias, and x-ray energy influence its performance and non-ideal effects.

Contribution

It provides a detailed analysis of GaAs sensor properties and identifies key factors affecting its performance, such as temperature stability and bias voltage.

Findings

Hole trapping causes non-ideal effects

Sensor performance varies with temperature and bias

Proper temperature control is essential for optimal operation

Abstract

We studied the properties of chromium compensated GaAs when coupled to charge integrating ASICs as a function of detector temperature, applied bias and x-ray tube energy. The material is a photoresistor and can be biased to collect either electrons or holes by the pixel circuitry. Both are studied here. Previous studies have shown substantial hole trapping. This trapping and other sensor properties give rise to several non-ideal effects which include an extended point spread function, variations in the effective pixel size, and rate dependent offset shifts. The magnitude of these effects varies with temperature and bias, mandating good temperature uniformity in the sensor and very good temperature stabilization, as well as a carefully selected bias voltage.