Effects of Surface Treatments on Multilayered p‐n Contrast of GaN in Scanning Electron Microscopy

Reliable n‐type and p‐type GaN materials, achieved by doping donor and acceptor atoms, are a prerequisite for the application of GaN‐based devices. Dopant profiling (i.e., the two‐dimensional distribution of dopants) is critical to the development, diagnosis, and electrical performance enhancement of GaN‐based devices. With the continuous increase in device integration density, the feature size has been scaled down to 3 nm and beyond, presenting a severe challenge to dopant profiling technology. The Scanning Electron Microscope offers unique advantages for dopant profiling, including fast imaging speed, high spatial resolution, and ease of operation. In this study, dopant profiling of multilayered p‐n GaN samples was performed by SEM. Plasma treatment, ultraviolet irradiation as well as air exposure were employed to study the influence of surface treatments on doping contrast of multilayered p‐n GaN samples. Combined with the surface elemental composition, surface band bending extent, and surface roughness before and after surface modification, the underlying mechanisms of surface treatments on p‐n GaN doping contrast were elucidated based on three doping contrast mechanisms, that is, the metal–semiconductor contact, the local electric field, and the surface band bending. This study will benefit the application of SEM for effective characterization of doped semiconductors, analysis of doping contrast mechanism, as well as quantitative analysis of dopants through SEM images.