Scanning electron microscopy imaging of multilayer-doped GaN: Effects of surface band bending, surface roughness, and contamination layers on doping contrast.

This article investigates the effects of plasma and wet chemical surface treatments on doping contrast in multilayered p-n gallium nitride (GaN) semiconductors using scanning electron microscopy (SEM) and angle-resolved x-ray photoelectron spectroscopy (ARXPS). It finds that nitrogen (N₂) and air plasma treatments reduce surface band bending but fail to remove surface contamination layers such as gallium oxides and hydrocarbons, resulting in weakened doping contrast. Conversely, wet chemical treatments generally remove these contamination layers more effectively but increase surface roughness, which can also diminish doping contrast; notably, ammonium fluoride (NH₄F) treatment improves doping contrast despite a slight increase in roughness. These results highlight the complex interplay between surface band bending, contamination, and roughness in influencing SEM doping contrast and provide guidance for optimizing semiconductor surface preparation for accurate dopant profiling.