MICROWAVE AND FAR-INFRARED MAGNETO-OPTICAL STUDIES IN SEMICONDUCTORS: ELECTRON PARAMAGNETIC RESONANCE IN CADMIUM(1-X)MANGANESE(X)TELLURIUM AND ZINC(1-X)MANGANESE(X)TELLURIUM, AND MAGNETO-TRANSMISSION IN LEAD(.98)YTTERBIUM(.02)TELLURIUM.

摘要

Interaction between electromagnetic radiation and matter has been successfully used to examine the properties of materials. In this dissertation we present two studies of semiconductors using microwave and far-infrared radiation.; In the first part we present electron spin resonance measurements in diluted magnetic semiconductors Cd(,1-x)Mn(,x)Te and Zn(,1-x)Mn(,x)Te for 0.05 (LESSTHEQ) x (LESSTHEQ) 0.7, 1.5 (LESSTHEQ) T (LESSTHEQ) 300 K, and 3 (LESSTHEQ) (nu) (LESSTHEQ) 55 GHz. Over wide ranges of T and for all x the line broadens with increasing x and lowering T, but is Lorentzian and centered at g = 2.01. The broadening with decreasing T is well described by the empirical form exp(-T/T(,o)), and is similar to that observed in other disordered spin systems above the spin glass temperature, T(,sg). The x dependence of the linewidth changes at the site percolation threshold of an fcc lattice, with only nearest neighbor interactions. At lower temperatures the linewidth increases faster than the empirical form. At very low temperatures the line becomes asymmetric and shifts down in field. A random distribution of internal fields is introduced to account for the data. We find the shape, peak, and the width of the distribution to be given by those of the broadened resonance line.; In the second part, we present far-infrared magneto-transmission measurements in n-type Pb(,.98)Yb(,.02)Te film at 4.2 K in the Faraday configuration, (')B (PARLL) (')q (PARLL) 111 , using circularly polarized 119 (mu)m radiation in magnetic fields of up to 8 T. The transmission data, which could be well fit to calculated curves based on a model dielectric function, give the electronic parameters of the sample. The carriers are found to be unequally distributed in the 111 and valleys, consistant with substrate induced strain. The effective masses are m(,T) = 0.036 m(,o) and m(,L) = 0.21 m(,o). The carrier scattering rate is (H/2PI)/(tau) (TURN) 1 meV. The carriers scatter by the short range ionic core potential of Yb ions. The observed scattering cross section per Yb ion is 2 (ANGSTROM)('2). The positions of the cyclotron resonances disagree with those calculated from the six-band (')k (.) (')p model, using PbTe band parameters and the energy gap of Pb(,.98)Yb(,.02)Te. Agreement is obtained with 2P(,(PERP))('2)/m(,o) = 4.2 eV and 2P(,(PARLL))('2)/m(,o) = 0.4 eV (which are 2/3 of those in PbTe) and the far band parameters of PbTe.