Properties of N-polar AlGaN/GaN heterostructures and field effect transistors grown by metalorganic chemical vapor deposition

S. Keller, C. S. Suh, Z. Chen, R. Chu, S. Rajan, N. A. Fichtenbaum, M. Furukawa, S. P. DenBaars, J. S. Speck, U. K. Mishra

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79 Scopus citations

Abstract

Smooth N-polar GaN/ Alx Ga1-x N/GaN heterostructures with a different Al mole fraction were grown by metalorganic chemical vapor deposition on (0001) sapphire substrates with a misorientation angle of 4° toward the a -sapphire plane. The sheet electron density of the two-dimensional electron gas (2DEG), which formed at the upper GaN/ Alx Ga1-x N interface increased with an increasing Al-mole fraction in the Alx Ga1-x N layer and increasing silicon modulation doping, similar to the observations for Ga-polar heterostructures. The transport properties of the 2DEG, however, were anisotropic. The growth on vicinal substrates led to the formation of well ordered multiatomic steps during Alx Ga1-x N growth and the sheet resistance of the 2DEG parallel to the steps was about 25% lower than the resistance measured in the perpendicular direction. The fabricated devices exhibited a drain-source current, IDS, of 0.9 A/mm at a gate-source voltage +1 V. At a drain-source voltage of 10 V and IDS =300 mA/mm, current-gain and maximum oscillation frequencies of 15 and 38 GHz, respectively, were measured.

Original languageEnglish (US)
Article number033708
JournalJournal of Applied Physics
Volume103
Issue number3
DOIs
StatePublished - Feb 22 2008

All Science Journal Classification (ASJC) codes

  • Physics and Astronomy(all)

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