Two-dimensional gas of surface electrons in strongly doped InAs. Structure of sub-bands and the scattering mechanism

The parameters of a quasi two-dimensional electron gas in enriched n-InAs layers (n=2x1016 - 2x1018 cm-3) are investigated experimentally and theoretically. The population parameters of the two-dimensional sub-bands, the binding energies and cyclotron masses determined on the basis of an analysis of the capacitance magnetooscillations are in good agreement with the results of a quasiclassical calculation. For a large number of semiconductors and semimetals with a Kein dispersion law the theory predicts that the parameters of the 2D sub-bands should be close to each other; this is confirmed by comparing the experimental data for InAs and Hg1-xCdxTe (x<0.2) which are extreme representatives of this class of material. An analysis of the field dependences of the oscillation amplitudes indicate that scattering by ionized donors and surface roughnesses play a dominant role in the samples studied. Due to the nonparabolicity effect, intersub-band screening and intersub-band scattering, the contribution from less populated excited sub-bands to the integral conductivity may frequently exceed the contribution from the ground sub-band