Study of depth-dependent radiation-induced defects using coherent acoustic phonon spectroscopy

Abstract

ABSTRACTHere we study the effect of radiation-induced point defect distributions on the optical reflectivity signal in GaAs using coherent acoustic phonon spectroscopy. We demonstrate that the presence of point defects significantly modifies the optical response, allowing estimation of the depth-dependent defect distribution in a nondestructive and noninvasive manner. We show that the observed changes are dependent on defect-induced changes to the electronic structure, namely defect-induced band tailing of the direct 1.43eV band edge. This provides a method for subsurface investigations on the complex interaction between different defects species and optoelectronic structure.