New Method of the Determination of HgCdTe/CdZnTe Composition by Infrared Transmission

概要

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A new method for compositional determination in Hg_<1-x>Cd_xTe/CdZnTe has been studied. In case of Hg_<1-x>Cd_xTe (MCT) epilayer grown onto Cd(Zn)Te substrates by liquid phase epitaxy (LPE), compositional graded region exists between the substrate and epilayer. This compositional graded region affects the infrared (IR) transmission curve. In this study, the IR transmission curves as a function of compositional profile and epilayer thickness were simulated based on the theoretical IR transmission model. From these results, a new and simple equation for calculating the composition of an epilayer MCT was obtained. This equation is related to the wavenumber (Z_<1/2>) of the 50% T_<max> transmission point, where T_<max> is the maximum transmission, the wavenumber (Z_<500>) of the 500 cm^<-1> absorption coefficient point, and the wavenumber (Z_<1000>) of the 1000 cm^<-1> absorption coefficient point. This equation is as follows: x = a+b×Z+(c+d×Z)×ln(10/T), where Z is the specific wavenumber in cm^<-1>, T is the epilayer thickness in μm, and a, b, c, and d are fitting parameters depending on the specific wavenumber. The compositions can be calculated easily using the new equation with an accuracy of ±0.002 in the range of 0.17 ≤ x ≤ 0.30. The new method can be also applied successfully to the samples with nonuniformity into depth and radial directions.
社団法人応用物理学会の論文
1996-01-15