Observation of persistent photoconductivity in bulk Gallium Arsenide and Gallium Phosphide samples at cryogenic temperatures using the Whispering Gallery mode method

TL;DR

This study investigates persistent photoconductivity in bulk Gallium Arsenide and Gallium Phosphide at cryogenic temperatures using Whispering Gallery modes, revealing decay times and the persistence of photoconductivity after light exposure.

Contribution

It demonstrates the application of Whispering Gallery mode technique to measure photoconductivity in bulk semiconductors at cryogenic temperatures, providing new insights into their decay dynamics.

Findings

Photoconductivity persists after white light exposure at cryogenic temperatures.

Decay time constants are approximately 0.9 ns for GaP and 1.1 ns for GaAs.

Whispering Gallery mode method effectively measures photoconductance in bulk samples.

Abstract

Whispering Gallery modes in bulk cylindrical Gallium Arsenide and Gallium Phosphide samples have been examined both in darkness and under white light at cryogenics temperatures < 50 K. In both cases persistent photoconductivity was observed after initially exposing semiconductors to white light from a halogen lamp. Photoconductance decay time constants for GaP and GaAs were determined to be 0.900 +/- 0.081 ns and 1.098 +/- 0.063 ns, respectively, using this method.