Cyclotron emission study of electron masses in GaAs-GaAlAs heterostructures
We study far-infrared cyclotron emission from GaAs-GaAlAs heterostructures, induced by electric pulses in the presence of a magnetic field and hydrostatic pressure. Cyclotron masses are measured as functions of 2D electron density in the strong electron heating regime at the pressures of P=0 and P=7 kbar. The results are described by an effective two-level k.p theory, which takes consistently into account the effect of band non-parabolicity on electric and magnetic quantization. It is shown that the observed emission spectrum is due to several transitions between Landau levels, since the 2D electron gas is non-degenerate. The same theory is used to describe cyclotron absorption data of other authors, obtained at zero and non-zero pressures under the conditions of degenerate electron gas. It is shown that the cyclotron absorption can be measured in two different regimes, which explains a strong dependence of the data on photon energy. A very good theoretical description of various emission and absorption experiments is achieved with the use of bulk GaAs parameters.