Dislocation and morphology control during molecular-beam epitaxy of AlGaN/GaN heterostructures directly on sapphire substrates

M. J. Manfra, N. G. Weimann, J. W.P. Hsu, L. N. Pfeiffer, K. W. West, S. N.G. Chu

Research output: Contribution to journalArticlepeer-review

39 Scopus citations

Abstract

We report on the growth and transport characteristics of high-density (∼1013cm-2) two-dimensional electron gases confined at the AlGaN/GaN interface grown by plasma-assisted molecular-beam epitaxy on sapphire substrates. For structures consisting of a 25 nm Al 0.30Ga0.70N barrier deposited on a 2 μm insulating GaN buffer, room-temperature mobilities averaging 1400cm2/Vs at a sheet charge density of 1.0×1013cm-2 are consistently achieved. Central to our approach is a sequence of two Ga/N ratios during the growth of the insulating GaN buffer layer. The two-step buffer layer allows us to simultaneously optimize the reduction of threading dislocations and surface morphology. Our measured sheet resistivities as low as 350/ compare favorably with those achieved on sapphire or SiC by any growth method. Representative current-voltage characteristics of high-electron-mobility transistors fabricated from this material are presented.

Original languageEnglish (US)
Pages (from-to)1456-1458
Number of pages3
JournalApplied Physics Letters
Volume81
Issue number8
DOIs
StatePublished - Aug 19 2002
Externally publishedYes

All Science Journal Classification (ASJC) codes

  • Physics and Astronomy (miscellaneous)

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