Surface evolution and effect of V/III ratio modulation on etch-pit-density improvement of thin AlN templates on nano-patterned sapphire substrates by metalorganic chemical vapor deposition

Tzu Yu Wang, Chi Tsung Tasi, Ku Yen Lin, Sin Liang Ou, Ray-Hua Horng, Dong Sing Wuu*

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

11 Scopus citations

Abstract

A low defect-density AlN template film using V/III ratio modulation and nano-patterned sapphire substrate (NPSS) was achieved by metalorganic chemical vapor deposition. In contrast to conventional high-quality AlN/NPSS obtained with high coalescence thickness (>6 μm) using high growth temperatures (≥1250 o C), this study reveals the high crystallinity of AlN with the lower thickness of 2.55 μm grown under a lower temperature of 1130 °C. It could effectively increase the heater lifetime and reduce the epi-wafer warpage. The growth of AlN/NPSS dominated by epitaxial lateral overgrowth achieves a dramatic reduction of full width at half maximum values along (101¯2) plane from 1640 to 714 arcsec, and lowest dislocation density of approximately 1 × 10 8 cm −2 , as well as a ultra-low etching pit density of 2.3 × 10 5 cm −2 . The crack-free AlN/NPSS with a compressive stress owing to the tensile stress was relaxed by the existence of some key-shaped holes upon the patterned region. Details of the surface evolution, mechanism and dislocation behavior of AlN/NPSS will be discussed and these results demonstrate this low-defect template technique of high potential for AlGaN-based device applications.

Original languageEnglish
Pages (from-to)1123-1130
Number of pages8
JournalApplied Surface Science
Volume455
DOIs
StatePublished - 15 Oct 2018

Keywords

  • AlN
  • Etch pit density
  • Nano-patterned sapphire
  • V/III ratio modulation

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