Quantum transport in n-type and p-type modulation-doped mercury telluride quantum wells

Asymmetrically modulation-doped HgTe quantum wells of (0 0 1) orientation were produced by molecular beam epitaxy. N-type doping was achieved with iodine and p-type doping by the incorporation of nitrogen. At 4.2 K the n-type samples have electron mobilities up tc 10(5) cm(2)/Vs, the maximum Hall mobility of the p-type specimens is around 2 x 10(4) cm(2)/Vs. Very pronounced Shubnikov-de Haas oscillations were observed in both n-type and p-type samples. In the n-type specimens the quantum oscillations persisted up to temperatures of 60 K. The Shubnikov-de Haas oscillations in the p-type samples were highly irregular. Because the data cannot be explained without detailed theoretical calculations of Landau levels for the heterostructure self consistent Hartree calculations were performed using a 8 x 8k . p model. The magnetic field-dependent density of states was calculated. More regular oscillations are predicted at higher magnetic fields approaching 30 T. (C) 2000 Elsevier Science B.V. All lights reserved.