MOLECULAR-BEAM EPITAXY OF MERCURY-IRON SELENIDE LAYERS AND QUANTUM-WELLS

Epitaxial layers and single quantum wells (SQW) of Fermi-level pinned mercury-iron selenide (HgSe:Fe) have been grown by molecular beam epit axy on ZnTe buffer layers and characterised by in- situ high-energy el ectron diffraction (RHEED) and high-field magnetospectroscopy investig ations. The onset of strain relaxation at the critical thickness has b een determined by time-dependent intensity-profile analysis of differe nt reflections in the RHEED pattern. A growth mode transition has been identified from 2D- to a 3D growth mode, which coincides exactly with the critical thickness equilibrium value of about 61 nm predicted by the Matthews-Blakeslee theory. Hall effect measurements have been perf ormed to determine the iron concentration in the HgSe layers below and above the Fermi-level pinning threshold-concentration. With increasin g iron concentration a pronounced increase of the mobility has been fo und in the layers according to the predictions of a short-range correl ation theory (SRC). The maximum carrier mobility of about 2.7 x 10(5) cm(-3) measured in a 1.5 mu m thick HgSe:Fe-layer indicates that long- range correlations have also to be considered in the transport mechani sm of mercury-iron selenide. Different types of HgSe:Fe-SQW and a HgSe :Fe/HgSe superlattice have been analyzed by Shubnikov-de Haas (SdH) me asurements and Hall effect measurements in magnetic fields up to 30 T. The existence of a two-dimensional electron system (Q2D) in the SQW h as been confirmed by the cosine dependence of the SdH-oscillation peri od. The dependence of the subband splitting in the SQW on the quantum well width has been investigated by Hall-resistance measurements.