Temperature dependent effective mass in AlGaN/GaN high electron mobility transistor structures

T. Hofmann, P. Kühne, S. Schöche, Jr Tai Chen, U. Forsberg, E. Janzén, N. Ben Sedrine, C. M. Herzinger, J. A. Woollam, M. Schubert, V. Darakchieva

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45 Scopus citations


The temperature-dependence of free-charge carrier mobility, sheet density, and effective mass of a two-dimensional electron gas in a AlGaN/GaN heterostructure deposited on SiC substrate is determined using the THz optical Hall effect in the spectral range from 0.22 to 0.32 THz for temperatures from 1.5 to 300 K. The THz optical Hall-effect measurements are combined with room temperature mid-infrared spectroscopic ellipsometry measurements to determine the layer thickness, phonon mode, and free-charge carrier parameters of the heterostructure constituents. An increase of the electron effective mass from (0.22 ± 0.01) m 0 at 1.5 K to (0.36 ± 0.03) m 0 at 300 K is observed, which is indicative for a reduction in spatial confinement of the two-dimensional electron gas at room temperature. The temperature-dependence of the mobility and the sheet density is in good agreement with electrical measurements reported in the literature.

Original languageEnglish (US)
Article number192102
JournalApplied Physics Letters
Issue number19
StatePublished - Nov 5 2012

ASJC Scopus subject areas

  • Physics and Astronomy (miscellaneous)


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