Exploration of the Limits to Mobility in Two-Dimensional Hole Systems in GaAs/AlGaAs Quantum Wells

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 $\times$ 10${}^{10}$ cm${}^{-2}$ to 1.9 $\times$ 10${}^{11}$ cm${}^{-2}$ finding a nonmonotonic dependence of mobility on density at T = 0.3 K. Surprisingly, a peak mobility of 2.3 $\times$ 10${}^6$ cm${}^2$/Vs was measured at a density of 6.5 $\times$ 10${}^{10}$ cm${}^{-2}$ with further increase in density resulting in reduced mobility. We discuss possible mechanisms leading to the observed non-monotonic density dependence of the mobility. Relying solely on interface roughness scattering to explain the observed drop in mobility at high density requires roughness parameters which are not consistent with measurements of similar electron structures. This leaves open the possibility of contributions from other scattering mechanisms at high density.

arXiv comment7 pages, 8 figures

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Cited by in corpus (9)

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• Record-quality GaAs two-dimensional hole systems
• Fractional Quantum Hall States in a Ge Quantum Well
• Interplay between phonon and impurity scattering in 2D hole transport
• Density-dependent two-dimensional optimal mobility in ultra-high-quality semiconductor quantum wells
• Linear non-hysteretic gating of a very high density 2DEG in an undoped metal-semiconductor-metal sandwich structure
• Ultraclean two-dimensional hole systems with mobilities exceeding 10${}^7$ cm${}^2$/Vs
• Impact of Short-Range Scattering on the Metallic Transport of Strongly Correlated 2D Holes in GaAs Quantum Wells