Characterization of the Substrate/Film Interface in GaN Films by Image Depth Profiling Secondary Ion Mass Spectrometry (Sims)

Abstract

Epitaxial GaN films are normally grown on substrates, such as sapphire, that are not an exact lattice match for GaN. Thus during the early stages of film growth, defects may be introduced in the film. These defects can lead to islanding and form voids or other defects just above the interface. These defects produce nonuniformity in the films and affect the quality of the final film. SIMS depth profiling is a widely used to characterize GaN films. The normal SIMS depth profiles provide chemical and depth information but do not provide any lateral information. We show that image depth profiling with SIMS is a technique that can be used to identify the defects and also chemically identify other interface features with lateral dimensions down to 1 μm.