Density and well width dependences of the effective mass of twodimensional holes in (100) GaAs quantum wells measured by cyclotron resonance at microwave frequencies

TL;DR

This study measures how the effective mass of two-dimensional holes in GaAs quantum wells varies with well width and hole density using cyclotron resonance, revealing strong dependences on these parameters.

Contribution

It provides new experimental data on the dependence of hole effective mass on well width and density in (100) GaAs quantum wells, using microwave cyclotron resonance.

Findings

Effective mass increases with hole density for fixed well width.

Effective mass increases with well width up to 30 nm, then saturates.

Measured effective mass ranges from 0.22 to 0.51 times the electron mass.

Abstract

Cyclotron resonance at microwave frequencies is used to measure the band mass (m_b) of the two-dimensional holes (2DH's) in carbon-doped (100) GaAs/AlxGa1-xAs heterostructures. The measured m_b shows strong dependences on both the 2DH density(p) and the GaAs quantum well width (W). For a fixed W, in the density range (0.4x10^11 to 1.1x10^11 cm^-2) studied here, m_b increases with p, consistent with previous studies of the 2DHs on the (311)A surface. For a fixed p = 1.1x10^11 cm^-2, mb increases from 0.22 m_e at W = 10 nm to 0.50 m_e at W = 30 nm, and saturates around 0.51 m_e for W > 30 nm.