Jl. Weyher et al., Growth of high quality, MOCVD grown Ga-polar GaN layers on GaN substrates after novel reactive ion etching, PHYS ST S-A, 176(1), 1999, pp. 573-577
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.