Effects of N/Ga flux ratio on GaN films grown on 4H-SiC substrate with 4° miscutting orientation by plasma-assisted molecular beam epitaxy

Iwan Susanto, Tsung Han Tsou, Zu-Po Yang, Chao Yu Lee, Hui Li, Ing Song Yu*

*Corresponding author for this work

Research output: Contribution to journalArticle

6 Scopus citations

Abstract

High-quality GaN films grown on 4H-SiC (0001) substrate with 4° of miscutting orientation have been done by plasma-assisted molecular beam epitaxy with different N/Ga flux ratio. The effect of N/Ga flux ratio on the surface morphology, chemical composition, structural and optical properties was systematically investigated. The observations of in-situ reflective high-energy electron diffraction demonstrated the special surface of SiC substrate and GaN growth transition from two-to three-dimension depending on N/Ga flux ratio. In the Ga-rich condition for epitaxy, Ga droplets formed and the root mean square value of surface roughness increased by the characterizations of scanning electron microscopy and atomic force microscopy which also related to the formation of the pits on the surface due to the accumulation of excess Ga on the surface. The better growth parameter of GaN films in the work is N/Ga flux ratio of 28 at substrate temperature 700 °C. Its surface oxide and charge-compensated surface state associated with defects are minimized from the surface composition analysis of X-ray photoelectron spectroscopy. In the structural characterization of high-resolution X-ray diffraction, the value of full width at half maximum and density of threading dislocation are lower to prove the high-quality structure of GaN film grown at N/Ga flux ratio of 28. Finally, the photoluminescence analysis performed the narrow near-band-edge peak and yellow band, corresponding to the better quality of GaN films. In this report, high-quality GaN films on 4H-SiC (0001) with 4° of miscutting orientation have been demonstrated by the reduction of defect states via the different N/Ga flux ratio. N/Ga flux ratio not only influences the growth mechanism and surface morphology, but also the surface chemical composition, crystal quality and optical properties of GaN compound semiconductors.

Original languageEnglish
Pages (from-to)800-808
Number of pages9
JournalJournal of Alloys and Compounds
Volume710
DOIs
StatePublished - 1 Jan 2017

Keywords

  • Compound semiconductor
  • Gallium nitride
  • Molecular beam epitaxy
  • Photoluminescence
  • Silicon carbide

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