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

Cyclotron resonance at microwave frequencies is used to measure the band mass (mb) of the two-dimensional holes (2DHs) in carbon- doped (100) GaAs/AlxGa1-xAs heterostructures. The measured mb shows strong dependences on both the 2DH density (p) and the GaAs quantum well width (W). For a fixed W, in the density range (0.4„e1011 to 1.1„e1011 cm-2) studied here, mb increases with p, consistent with previous studies of the 2DHs on the (311)A surface. For a fixed p = 1.1„e1011cm-2, mb increases from 0.22me at W = 10nm to 0.50 me at W = 30nm, and saturates around 0.51me for W > 30nm.