Studies of radiation damaged gallium arsenide using coherent acoustic phonon spectroscopy

Abstract

The operation and properties of semiconductor devices depends critically on a material’s electronic structure. Point defects, such as vacancy and interstitial defects that arise from operation in radiative atmospheres or during less-than-ideal growth processes, have a significant influence on electronic material properties and tend to degrade device operation. Here we show that a novel ultrafast time-resolved pump-probe technique, known as coherent acoustic phonon spectroscopy, is capable of non-destructive, quantitative, depth-dependent measurement of point defect profiles arising from ion irradiation in gallium arsenide. In the CAP response, defects are observable through reduction of the CAP oscillation amplitude, which is demonstrated to be connected to a decrease in the photoelastic constant at the 1.42 eV GaAs band-edge caused by defect-induced lattice strain. Finally, we present theoretical calculations that support our proposed model and agree well with experimental observations