TEMPERATURE AND COMPOSITION DEPENDENCE OF THE ENERGY-GAP OF HG1-XCDXTE BY 2-PHOTON MAGNETOABSORPTION TECHNIQUES

Accurate determinations of the energy gap Egat liquid helium temperatures in alloys of 0.24<jc< 0.30 have been made by two-photon magnetoabsorption techniques. They are shown to help verify the use of the Hansen-Schmit-Casselman (HSC) relation over the range 0 <x <0.30 at these temperatures. In contrast, the observed temperature dependence of Egbelow 77 K is nonlinear and thus cannot be described accurately by the HSC relation. Analysis of Eg(T) data for three samples with 0.24<x<0.26 has allowed the deduction of a new relationship for Eg{x,T) that more properly accounts for the nonlinear temperature dependence below 77 K and the linear behavior above 77 K, while still accurately describing the x dependence Eg(x,T) =-0.302 + 1.93x + 5.35(1-2x) (10-4) [(-1822 + T)/ (255.2 + T)]-0.810x + 0.832.x, for Egin eV and Tin K. This relation should apply to alloys with 0.2 <x < 0.3. The maximum change from the HSC relation in this range is 0.004 eV for x = 0.2 at — 10 K. © 1990, American Vacuum Society. All rights reserved.