Dresden 2003 – wissenschaftliches Programm
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HL: Halbleiterphysik
HL 34: Transporteigenschaften
HL 34.8: Vortrag
Mittwoch, 26. März 2003, 18:30–18:45, POT/81
Magnetotransport Studies on Three Dimensional Electron Gases in AlGaN/GaN Heterostructures — •Link Angela1, Oliver Ambacher2, Debdeep Jena3, Umesh Mishra3, Jim Speck3 und Martin Stutzmann1 — 1Walter Schottky Institut, Am Coulombwall 3, 85748 Garching — 2Zentrum für Mikro- und Nanotechnologie, TU Ilmenau, 98684 Ilmenau — 3Department of Electrical and Computer Engineering, University of California, Santa Barbara, California 93106, USA
The experimental realization of three dimensional electron slabs (3DES) was achieved by exploiting the large polarisation charges in III-V nitrides [1]: Grading the AlGaN/GaN heterojunction over a distance of 100 nm by a linear change of the Al-content, spreads the positive polarization charge into a bulk 3D polarization background charge. The resulting 3D electron gas has a very high carrier mobility of 3000 cm2/Vs at 330 mK due to the absence of scattering by shallow donors. This has allowed us to observe quantum effects in low temperature magnetotransport measurements. In particular, from the temperature dependence of the Shubnikov-de Haas (SdH) oscillations, the average effective mass of the 3D electrons was determined to 0.19 m0. Furthermore, angle resolved SdH investigations revealed the 3D character of the spread electrons. A detailed analysis of the angular dependence indicates a possible mass anisotropy.
[1] D. Jena et al., Appl. Phys. Lett. 81, 4395 (2002)