BGaN micro-islands as novel buffers for growth of high-quality GaN on sapphire

Tetsuya Akasaka, Yasuyuki Kobayashi, Toshiki Makimoto

Research output: Contribution to journalArticle

7 Citations (Scopus)

Abstract

We discuss the growth mechanism of GaN films and report very high two-dimensional electron gas (2DEG) mobility in AlGaN/AlN/GaN heterostructures fabricated on sapphire using BGaN micro-islands as novel buffers by metalorganic vapor phase epitaxy. The three-dimensional growth of BGaN (formation of BGaN micro-islands) occurs due to the phase separation of BGaN. However, the surface of the overgrown GaN on the BGaN micro-islands becomes smooth and continuous through the epitaxial lateral overgrowth process. The threading dislocations (TDs) in GaN consist mainly of pure edge-type ones and are effectively annihilated using single and double layers of BGaN micro-islands from 2×1010 to 2×109 and 2×108 cm-2, respectively. An n-type GaN film shallowly doped with Si exhibits an electron concentration and high Hall mobility of 3.0×1016 cm-3 and 669 cm2/Vs at room temperature (RT). Very high Hall 2DEG mobility in an Al0.10Ga0.90N/AlN/GaN heterostructure is obtained: 1910 and 20,600 cm2/Vs at RT and 77 K, respectively. The sheet carrier density had almost constant values of 6.9-5.7×1012 cm-2 in the temperature range from 77 to 500 K, indicating that the parallel conduction due to the residual electrons in the GaN underlying layer was negligible.

Original languageEnglish
Pages (from-to)320-324
Number of pages5
JournalJournal of Crystal Growth
Volume298
Issue numberSPEC. ISS
DOIs
Publication statusPublished - 2007 Jan
Externally publishedYes

Fingerprint

Two dimensional electron gas
Aluminum Oxide
Sapphire
Buffers
sapphire
buffers
Heterojunctions
Hall mobility
Metallorganic vapor phase epitaxy
Electrons
Phase separation
Temperature
Carrier concentration
room temperature
vapor phase epitaxy
electron gas
electrons
conduction
temperature

Keywords

  • A3. Low-pressure metalorganic vapor phase epitaxy
  • B1. Nitrides
  • B2. Semiconducting III-V materials

ASJC Scopus subject areas

  • Condensed Matter Physics

Cite this

BGaN micro-islands as novel buffers for growth of high-quality GaN on sapphire. / Akasaka, Tetsuya; Kobayashi, Yasuyuki; Makimoto, Toshiki.

In: Journal of Crystal Growth, Vol. 298, No. SPEC. ISS, 01.2007, p. 320-324.

Research output: Contribution to journalArticle

Akasaka, Tetsuya ; Kobayashi, Yasuyuki ; Makimoto, Toshiki. / BGaN micro-islands as novel buffers for growth of high-quality GaN on sapphire. In: Journal of Crystal Growth. 2007 ; Vol. 298, No. SPEC. ISS. pp. 320-324.
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