Modified permittivity observed in bulk Gallium Arsenide and Gallium Phosphide samples at 50 K using the Whispering Gallery mode method

TL;DR

This study investigates how the permittivity of bulk Gallium Arsenide and Gallium Phosphide changes at 50 K under light and dark conditions using Whispering Gallery modes, revealing effects of free photocarriers on dielectric properties.

Contribution

It demonstrates the modification of permittivity in bulk semiconductors due to photo-induced free carriers, measured via Whispering Gallery mode technique at cryogenic temperatures.

Findings

Permittivity changes under illumination and darkness.

Surface free carriers influence dielectric properties.

Polarization state affected by electron-hole dynamics.

Abstract

Whispering Gallery modes in bulk cylindrical Gallium Arsenide and Gallium Phosphide samples have been examined both in darkness and under white light at 50 K. In both samples we observed change in permittivity under light and dark conditions. This results from a change in the polarization state of the semiconductor, which is consistent with a free electron-hole creation/recombination process. The permittivity of the semiconductor is modified by free photocarriers in the surface layers of the sample which is the region sampled by Whispering Gallery modes.