Photoconductivity and Thermoelectric Power of Zn_xCd_<1-x>Se Films

概要

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Zn_xCd_<1-x>Se (0≤x≤1) films were deposited by two zone hot wall evaporation technique. X-ray diffraction analysis of the films indicated a predominant wurtzite structure for x<0.5, which changed to zinc blende structure for x>0.7. The films had a mixed structure for 0.5<x<0.7. The films were highly resistive (resistivity varying within 3 Ω・cm to 1.5×10^5 Ω・cm for 0<x<1.0) with partially depleted grains. The optical band gap (E_g), determined from the reflectance measurements, indicated a direct transition with a bowing effect in E_g versus x plot. The conductivity at low temperature (for x<0.6) could be explained by thermionic emission over the intercrystalline barrier, while for higher x quantum mechanical tunneling through the barrier became predominant. The variation of the barrier height (E_<bd>) with the intensity of illumination was obtained from the photoconductivity measurements. The majority carrier capture cross-section (1-4×10^<-18>cm^2) of the grain boundary traps (1×10^<11>-1×10^<12>cm^<-2>) was determined. The effect of the intercrystalline barrier on the thermoelectric power measurements was also considered.
社団法人応用物理学会の論文
1995-09-15