Formation Characteristics of Inversion Domains in P-GaN and P-AlGaN Layers By Using TEM Observation

The formation characteristics of the inversion domains in p-GaN and p-AlGaN layers were investigated by using transmission electron microscopy (TEM). The inversion domains induced by Mg-doped p-type GaN (p-GaN) and p-AlGaN layers were formed on a sapphire substrate by using a metalorganic chemical vapor deposition (MOVCD) method. The induced inversion domains were analyzed by using high-resolution TEM (HRTEM) and convergent beam electron di raction (CBED) and the residual strain distribution was evaluated by using a strain mapping simulation. The results revealed that pyramidal defects of various sizes were formed at the p-GaN/p-AlGaN interface. Also, a large number of inversion domains were observed to be initiated exclusively on (0002) plane of the pyramidal defects, which were above 10 nm toward the [000 1] direction, resulting in a rough, island-shaped p-GaN surface due to the inhibition of GaN growth by the inversion domains. In this study, the formation characteristics of inversion domains were correlated with the in uence of structural defects existing at the p-GaN/p-AlGaN interface.