1. Transport Properties of Two-Dimensional Electron Gases Induced by Spontaneous and Piezoelectric Polarisation in AlGaN/GaN Heterostructures
- Author
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Martin Stutzmann, T. Graf, Oliver Ambacher, James S. Speck, Y. Smorchkova, Roman Dimitrov, A. Link, and Umesh K. Mishra
- Subjects
Condensed matter physics ,Hall effect ,Scattering ,Chemistry ,Heterojunction ,Electron ,Scattering theory ,Electronic structure ,Condensed Matter Physics ,Electron scattering ,Molecular physics ,Shubnikov–de Haas effect ,Electronic, Optical and Magnetic Materials - Abstract
We have performed Shubnikov-de Haas (SdH) and Hall effect measurements to investigate the electronic transport properties of polarisation induced 2DEGs in Al x Ga 1-x N/GaN heterostructures with alloy compositions between x = 0.10 and 0.35 and sheet carrier concentrations of up to n s = 1.05 × 10 13 cm -2 . From SdH measurements of 2DEGs with sheet carrier concentrations of 2.1 × 10 12 and 4.6 × 10 12 cm -2 , effective electron masses were determined to be 0.24 and 0.207m 0 , respectively. In addition, angle resolved SdH measurements were performed to evaluate the effective g-factor from the angle of zero oscillation amplitude. Including the measured electron masses, the g-factors were calculated to be 2.11 and 2.47, respectively. In order to identify the main electron scattering mechanism we determined the ratio between transport- and quantum scattering times as a function of sheet carrier concentration. We observe a significant decrease of the τ t /τ q ratio with increasing 2DEG carrier concentration, indicating a transition from a dominant small angle to large angle scattering mechanism when n s exceeds 7 × 10 12 cm -2 .
- Published
- 2001