Growth of high quality, MOCVD grown Ga-polar GaN layers on GaN substrates after novel reactive ion etching

In this paper we present morphological, structural, optical and chemical ch aracteristics of GaN homoepitaxial layers grown by MOCVD on Ga-polar (0001) substrates prepared using a novel reactive ion etching (RIE) procedure. Th e layers show microscopically featureless morphology and exhibit the step-f low growth mode with step heights of c/2 as evidenced by DIC optical and at omic force microscopy, respectively. Cross-sectional TEM illustrated the ab sence of threading defects. Low temperature (4.2 K) photoluminescence from this defect-free layer shows donor- and acceptor-bound exciton peaks with l inewidth below 1 meV. Secondary ion mass spectroscopy revealed an abrupt ch ange of the concentration of all the typical contaminants (O, C, Si, H) acr oss the epilayer/substrate interface. The results indicate that the RIE pro cess based on Ar-SiCl4-SF6 chemistry is the right tool for preparing Ga-pol ar GaN substrates for the growth of high quality homoepitaxial layers.