MAGNETOCONDUCTANCE SPECTROSCOPY OF A NARROW-GAP HG1-XCDXTE (X-APPROXIMATE-TO-0.2) MIS DEVICE

The equivalent parallel capacitance C-m and conductance G(m) of a meta l-insulator-semiconductor (MIS) device prepared on tow-concentration p -type Hg1-xCdxTe (x approximate to 0.2) exhibit, in an external magnet ic field, well-resolved oscillations both as a function of gate voltag e V-g and magnetic field B, when biased into inversion. The oscillatio ns result from a magnetic-field-induced modulation of the two-dimensio nal (2D) density of states (Landau levels) either in the inversion lay er developed under the MIS gate contact (when measured at fixed B) or in the inverted surface under the passivating anodic oxide layer in th e area surrounding the gate (when measured as a function of B with V-g kept constant). The minority carrier transport mechanism is discussed and by using Fourier analysis of the observed oscillations, the numbe r and partial occupancies of the 2D quantized subbands of the inverted surface layer are deduced. The shallow acceptor activation energy E(a ) = 4.4 +/- 0.2 meV is evaluated from the observed carrier freeze-out.