Study of the partial decomposition of GaN layers grown by MOVPE with different coalescence degree

•The GaN decomposition was studied in MOVPE reactor under N2 at 1200 °C.•The increase of the amount of non-c plane leads to faster decomposition.•The crystalline property of decomposed GaN are similar to the as grown.

We investigated the partial decomposition of GaN layers grown with different coalescence degrees by atmospheric pressure metal organic vapor phase epitaxy (AP-MOVPE) on SiN treated sapphire substrate. The decomposition was performed in AP-MOVPE reactor under nitrogen (N2) flow at 1200 °C. The growth and decomposition processes were in-situ monitored by laser reflectometry (LR) at normal incidence. Surface morphology, crystalline and optical properties of GaN layers were examined before and after partial decomposition by scanning electron microscope (SEM) and high resolution X-ray diffraction (HRXRD). Low decomposition rate and low surface degradation were obtained for thick and most coalesced GaN layers. The partial decomposition did not significantly affect the optical and crystalline properties of GaN. In particular, HRXRD showed almost the same full width at halfmaximum (FWHM) of (00.2) and (10.2) rocking curves (RCs) before and after partial decomposition of coalesced GaN layer.