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Dresden 2006 – scientific programme

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HL: Halbleiterphysik

HL 9: Poster I

HL 9.102: Poster

Monday, March 27, 2006, 15:15–17:45, P3

Characterization of AlGaN/GaN - heterostructures by means of magnetotransport measurements in high magnetic fields — •K. Knese1, F. Vogt1, N. Riedel1, U. Rossow1, E. Sagol2, Ch. Stellmach1, and G. Nachtwei11Institut für Angewandte Physik, Technische Universität Braunschweig, Mendelsohnstr. 2, D-38106 Braunschweig — 2Physikalisch Technische Bundesanstalt, Bundesallee 100, D-38116 Braunschweig

The group-III-nitrides are very promising materials in terms of high power, high temperature and high frequency electronic applications. In this work, we investigate the electronic properties of a two dimensional electron gas (2DEG) in AlGaN/GaN heterostructures grown on sapphire substrates in order to obtain a better understanding of scattering mechanisms and transport properties. Therefore, Shubnikov-de Haas (SdH)- and Hall-measurements were performed on several samples (in Hall bar- and Van der Pauw- geometry) with different Al-content of the AlGaN-barrier in high magnetic fields up to 18 T. From SdH- and Hall- measurements the sheet carrier concentration was determined to be 4·1012 - 1·1013 cm−2. The analysis of temperature-dependent SdH-oscillations yields an electronic effective mass of 0.23 - 0.26 m0. In addition, the quantum scattering lifetime τt, which is related to the Landau level broadening, and the classical lifetime τD can be calculated from such measurements, whereas the ratio τtD is an indicator of the type of scattering mechanism present in the sample. Finally, the effective Landé-factor g* was determined from angular dependent SdH-measurements.

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