Abstract

We report on the growth and electrical characterization of a series of two-dimensional hole systems (2DHSs) used to study the density dependence of low temperature mobility in 20-nm GaAs/AlGaAs quantum wells. The hole density was controlled by changing the Al mole fraction and the setback of the delta-doping layer. We varied the density over a range from 1.8 x 10(10) cm(-2) to 1.9 x 10(11) cm(-2) finding a nonmonotonic dependence of mobility on density at T = 0.3 K. Surprisingly, a peak mobility of 2.3 x 10(6) cm(2)/Vs was measured at a density of 6.5 x 10(10) cm(-2), with further increase in density resulting in reduced mobility. We discuss possible mechanisms leading to the observed nonmonotonic density dependence of the mobility. Relying solely on interface roughness scattering to explain the observed drop in mobility at high density requires roughness parameters that are not consistent with measurements of similar electron structures. This leaves open the possibility of contributions from other scattering mechanisms at high density.

Comments

This is the published version of J. D. Watson, S. Mondal, G. Gardner, G. A. Csáthy, and M. J. Manfra. 3 April 2012. Exploration of the limits to mobility in two-dimensional hole systems in GaAs/AlGaAs quantum wells. First published in the Physical Review B and is available online at: http://dx.doi.org/10.1103/PhysRevB.85.165301

Keywords

ALLOY SCATTERING; ELECTRON-GAS; GAAS; DENSITY; HETEROSTRUCTURES; SEMICONDUCTOR; HETEROJUNCTIONS; ALXGA1-XAS; LAYERS; SPIN

DOI

10.1103/PhysRevB.85.165301

Citation

Exploration of the limits to mobility in two-dimensional hole systems in GaAs/AlGaAs quantum wells J. D. Watson, S. Mondal, G. Gardner, G. A. Csáthy, and M. J. Manfra Phys. Rev. B 85, 165301 – Published 3 April 2012

Date of this Version

4-3-2012

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