Study of Electron Accumulation Layers on Mercury - - Telluride Using Surface Potential-Modulated Shubnikov - Haas Measurements and Determination of Electrical Transport Properties Using a Novel Magnetic Field-Dependent Hall Technique.

The oscillatory transport properties of accumulation layers on n-type Hg(,0.8)Cd(,0.2)Te have been measured at magnetic fields up to 4.5 Tesla using a gate modulation technique. Three distinct Shubnikov-de Haas oscillation frequencies, corresponding to three electric subbands, were observed and analyzed using the best recursive fit technique. The effective mass and Dingle temperature for each of the subbands is reported. The Dingle temperature decreases with subband number and two mechanisms are proposed to explain the effect. Also, a novel technique is presented for interpreting magnetic field-dependent Hall data at magnetic fields below the range at which Shubnikov-de Haas oscillations occur. The technique generates a "mobility spectrum" in which the maximum carrier density or maximum conductivity is determined as a continuous function of mobility. Unlike previous procedures, the technique does not require advance knowledge of the number of different types of carriers or the carrier properties, so that ambiguities in the analysis are avoided. Examples of the use of the technique with synthetic data as well as data from (Hg,Cd)Te and GaAs/AlGaAs samples are provided. Other uses of the procedure, including measurement of Fermi surface shapes is discussed.