Effect of the misorientation of the 4H-SiC substrate on the open volume defects in GaN grown by metal organic chemical vapour deposition

Abstract

Positron annihilation spectroscopy has been used to study GaN grown by metal-organic chemical vapor deposition on misoriented 4H-SiC substrates. Two kinds of vacancy defects are observed: Ga vacancies and larger vacancy clusters in all the studied layers. In addition to vacancies, positrons annihilate at shallow traps that are likely to be dislocations. The results show that the vacancy concentration increases and the shallow positron trap concentration decreases with the increasing substrate misorientation.