Unintentionally doped n-type Al 0.67Ga 0.33N epilayers

M. L. Nakarmi, N. Nepal, J. Y. Lin, H. X. Jiang

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Unintentionally doped Al0.67 Ga0.33 N epilayers were grown on AlNsapphire templates by metalorganic chemical vapor deposition. Optimized undoped Al0.67 Ga0.33 N epilayers exhibited an n -type conductivity as confirmed by Hall-effect measurement with a room-temperature resistivity of about 85 Ω cm. Variable temperature Hall-effect measurement revealed the existence of a shallow donor level with activation energy of about 90 meV. The photoluminescence (PL) spectra exhibited an emission peak at 4.13 eV (4.06 eV) related to an impurity transition at 10 K (300 K). Temperature dependent PL measurement also confirmed the existence of a shallow donor with comparable activation energy as that obtained by Hall-effect measurement. Isolated oxygen impurities are believed to be a strong candidate of the donor that remains as a shallow state in Alx Ga1-x N up to x∼0.7. Compensating defects and the nature of the O donor in Al0.67 Ga0.33 N epilayers are also discussed.

Original languageEnglish
Article number261902
Pages (from-to)1-3
Number of pages3
JournalApplied Physics Letters
Issue number26
StatePublished - Jun 27 2005


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