Comparison of stress states in GaN films grown on different substrates: Langasite, sapphire and silicon

Byung Guon Park, R. Saravana Kumar, Mee Lim Moon, Moon Deock Kim, Tae Won Kang, Woo Chul Yang, Song Gang Kim

Research output: Contribution to journalArticlepeer-review

37 Scopus citations

Abstract

We demonstrate the evolution of GaN films on novel langasite (LGS) substrate by plasma-assisted molecular beam epitaxy, and assessed the quality of grown GaN film by comparing the experimental results obtained using LGS, sapphire and silicon (Si) substrates. To study the substrate effect, X-ray diffraction (XRD), scanning electron microscopy (SEM), Raman spectroscopy and photoluminescence (PL) spectra were used to characterize the microstructure and stress states in GaN films. Wet etching of GaN films in KOH solution revealed that the films deposited on GaN/LGS, AlN/sapphire and AlN/Si substrates possess Ga-polarity, while the film deposited on GaN/sapphire possess N-polarity. XRD, Raman and PL analysis demonstrated that a compressive stress exist in the films grown on GaN/LGS, AlN/sapphire, and GaN/sapphire substrates, while a tensile stress appears on AlN/Si substrate. Comparative analysis showed the growth of nearly stress-free GaN films on LGS substrate due to the very small lattice mismatch (~3.2%) and thermal expansion coefficient difference (~7.5%). The results presented here will hopefully provide a new framework for the further development of high performance III-nitride-related devices using GaN/LGS heteroepitaxy.

Original languageEnglish
Pages (from-to)149-153
Number of pages5
JournalJournal of Crystal Growth
Volume425
DOIs
StatePublished - 28 Jul 2015

Keywords

  • A1. Stress
  • A1. Substrate
  • A3. Molecular beam epitaxy
  • B1. Gallium compounds
  • B1. Nitrides
  • B2. Semiconducting III-V materials

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