OPTICAL AND MAGNETOTRANSPORT PROPERTIES OF SEMIMETALLIC INAS (IN,GA)SB SUPERLATTICES/

Semimetallic superlattices and double heterojunctions of the system In As/InxGa1-xSb have been studied by cyclotron resonance and magnetotran sport in the magnetic field range 10-100 T. The cyclotron resonance is used to show that there is a magnetic field induced transition from s emimetallic to semiconducting behaviour, at which almost all the carri ers in the system disappear. The magnetotransport shows that large osc illatory Hall voltages occur in the quantised regime, and these are st rongly temperature dependent. The field positions of the Hall resistiv ity peaks are related to the crossing of the electron and hole Landau levels. Hydrostatic pressure is used to achieve a controlled decrease of the band overlap, and to show that the Hall peaks and minima move t o zero field as the zero overlap condition is approached. Both the cyc lotron resonance and the magnetotransport show that the magnitude of t he band overlap is orientation dependent, being approximately 60 meV l arger for (111) oriented structures. This is attributed to the presenc e of a large interface dipole for this orientation.