Coherent growth of r‐plane GaN films on ZnO substrates at room temperature

Abstract

AbstractWe grew semipolar r‐plane GaN films on ZnO substrates at room temperature (RT) by pulsed laser depositon (PLD). The structural characteristics of r‐plane GaN films grown on nearly lattice‐matched ZnO substrates at RT were investigated by X‐ray diffraction and reciprocal space mapping (RSM). The r‐plane GaN films grown on ZnO exhibited the narrowest X‐ray rocking curves of any heteroepitaxial semipolar GaN films. The improvement in crystalline quality achieved by the use of ZnO substrates was attributed to the coherent growth of r‐plane GaN under non‐equilibrium conditions by PLD. Symmetric RSM revealed that r‐plane GaN grows on ZnO substrates without the tilting of the r‐plane that was often observed in lattice‐mismatched semipolar growth. These results indicated that the formation of misfit dislocations at the GaN/ZnO interface is suppressed by coherent growth at RT.