HVPE growth of GaN layers on cleaved β-Ga_2O_3 substrates

摘要

GaN epitaxial layers were successfully grown by hydride vapour phase epitaxy (HVPE) on β-Ga_2O_3 substrates produced by cleaving. The initial stages of GaN epitaxial growth on β-Ga_2O_3 were studied by scanning electron microscopy (SEM) and x-ray diffraction analysis (XRD). The nucleation and the transition from the nucleation layer to a continuous GaN film were studied. It was found that the growth starts with formation of small crystallites on the substrate surface. As the growth continues, crystallites transform into pyramidal islands which increase in size and merge together. It was found that the structural quality of the GaN layers rapidly improves with increasing thickness. The full width at half maximum of x-ray co rocking curves for (0002) peak decreased from 1370 to 410 arcsec as the deposition time was increased from 30 to 1200 sec. This corresponds to the variation of the nominal layer thickness from 250 nm to 10 μm.