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

Cyclotron resonance at microwave frequencies is used to measure the band mass ( m b ) of the two-dimensional holes (2DHs) 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 (0.4×1011 to 1.1×1011 cm−2) studied here, m b increases with p , consistently with previous studies of the 2DHs on the (311)A surface. For a fixed p = 1.1 × 10 11 cm − 2 , m b 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 .