Density of states in a two-dimensional hole gas in high magnetic fields

We have investigated the temperature dependence of Shubnikov-de Haas (SdH) oscillations in p-type GaAs/(AlGa)As heterostructures at high magnetic fields and low temperatures (0.35–4.2 K). From both the temperature and the magnetic field dependence of the SdH minima the density of states (DOS) and the activation energies in the localized region between adjacent Landau levels were determined. The background DOS between two Landau levels reaches a substantial fraction of that at zero magnetic field.