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.

7 pages, 8 figures

References in corpus (6)

• Spin relaxation and decoherence of holes in quantum dots
• Limit to 2D mobility in modulation-doped GaAs quantum structures: How to achieve a mobility of 100 millions
• Fabrication and characterisation of ambipolar devices on an undoped AlGaAs/GaAs heterostructure
• Density and well width dependences of the effective mass of twodimensional holes in (100) GaAs quantum wells measured by cyclotron resonance at microwave frequencies
• Impact of spin-orbit coupling on quantum Hall nematic phases
• Scattering Mechanisms in a High Mobility Low Density Carbon-Doped (100) GaAs Two-Dimensional Hole System

Cited by in corpus (2)

• Record-quality GaAs two-dimensional hole systems
• Interplay between phonon and impurity scattering in 2D hole transport