Reduction of defects in AlGaN grown on nanoscale-patterned sapphire substrates by hydride vapor phase epitaxy

Chi Tsung Tasi, Wei Kai Wang, Tsung Yen Tsai, Shih Yung Huang, Ray-Hua Horng, Dong Sing Wuu*

*Corresponding author for this work

Research output: Contribution to journalArticle

3 Scopus citations

Abstract

In this study, a 3-μm-thick AlGaN film with an Al mole fraction of 10% was grown on a nanoscale-patterned sapphire substrate (NPSS) using hydride vapor phase epitaxy (HVPE). The growth mechanism, crystallization, and surface morphology of the epilayers were examined using X-ray diffraction, transmission electron microscopy (TEM), and scanning electron microscopy at various times in the growth process. The screw threading dislocation (TD) density of AlGaN-on-NPSS can improve to 1-2 × 10 9 cm -2 , which is significantly lower than that of the sample grown on a conventional planar sapphire substrate (7 × 10 9 cm -2 ). TEM analysis indicated that these TDs do not subsequently propagate to the surface of the overgrown AlGaN layer, but bend or change directions in the region above the voids within the side faces of the patterned substrates, possibly because of the internal stress-relaxed morphologies of the AlGaN film. Hence, the laterally overgrown AlGaN films were obtained by HVPE, which can serve as a template for the growth of ultraviolet III-nitride optoelectronic devices.

Original languageEnglish
Article number605
JournalMaterials
Volume10
Issue number6
DOIs
StatePublished - 31 May 2017

Keywords

  • AlGaN
  • Dislocation density (TD)
  • Hydride vapor phase epitaxy (HVPE)
  • Nanoscale-patterned sapphire substrate (NPSS)

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