Photoreflectance of AlxGa1-xAs and Al xGa1-xAs/GaAs interfaces and high-electron-mobility transistors

Michael Sydor, Neal Jahren, W. C. Mitchel, W. V. Lampert, T. W. Haas, M. Y. Yen, S. M. Mudare, D. H. Tomich

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Photoreflectance is used to measure AlxGa1-xAs composition, and to determine carrier concentrations in Si-doped AlGaAs epilayers capped with GaAs. Undoped caps are generally depleted, and do not show a usual GaAs photoreflectance. However, photoreflectance from the cap/(doped AlGaAs) interface produces a broad signal which distorts the entire spectrum, making it hard to locate the GaAs and AlGaAs band edges precisely. A similar broad signal from modulation-doped heterostructures is apparently associated with samples that show the presence of two-dimensional electron gas.

Original languageEnglish (US)
Pages (from-to)7423-7429
Number of pages7
JournalJournal of Applied Physics
Issue number12
StatePublished - Dec 1 1990

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