Accurate ultra-low-energy secondary ion mass spectrometry analysis of wide bandgap GaN/InxGa1-xN structures using optical conductivity enhancement

Ultra-low-energy secondary ion mass spectrometry has been used to undertake a structural analysis of GaN-InxGa1-xN (x similar to 0.25) quantum wells used in optoelectronic devices. The high resistivity of intrinsic GaN-InxGa1-xN restricts the necessary electrical path between the analyzed area and the instrument ground potential resulting in surface charge accumulation. Consequently, unstable and unrepresentative depth profiles tend to be produced. A technique known as optical conductivity enhancement (OCE) has been used during depth profiling to reduce the material resistivity. This creates an electrical path between the sample and holder, eliminating charge build up and resulting in accurate depth profiles.