Regular Issue Paper

Journal of Electronic Materials

, Volume 29, Issue 4, pp 411-417

Surface etching of 6H-SiC (0001) and surface morphology of the subsequently grown GaN via MOCVD

  • Z. Y. XieAffiliated withDepartment of Chemical Engineering, Kansas State University
  • , C. H. WeiAffiliated withDepartment of Chemical Engineering, Kansas State University
  • , S. F. ChenAffiliated withDepartment of Chemical Engineering, Kansas State University
  • , S. Y. JiangAffiliated withDepartment of Chemical Engineering, Kansas State University
  • , J. H. EdgarAffiliated withDepartment of Chemical Engineering, Kansas State University

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Abstract

The correlation between surface morphological properties of the GaN epilayers and the surface conditions of 6H-SiC (0001) substrates etched in H2, C2H4/H2, and HCl/H2 was studied. Etching 6H-SiC in H2 produced a high quality surface with steps and terraces, while etching in HCl/H2 produced either a rough surface with many pits and hillocks or a smooth surface similar to that etched in H2, depending on the HCl concentration and temperature. The GaN epilayers were subsequently deposited on these etched substrates using either a low temperature GaN or a high temperature AlN buffer layer via MOCVD. The substrate surface defects increased the density and size of the “giant” pinholes (2–4 µm) on GaN epilayers grown on a LT-GaN buffer layer. Small pinholes (<100 nm) were frequently observed on the samples grown on a HT-AlN buffer layer, and their density decreased with the improved surface quality. The non-uniform GaN nucleation caused by substrate surface defects and the slow growth rate of \(\{ 1\bar 101\} \) planes of the islands were responsible for the formation of “giant” pinholes, while the small pinholes were believed to be caused by misfit dislocations.

Key words

GaN etching MOCVD pinhole nanopipe