Precipitation in CdTe crystals studied through mie scattering

Infrared transmission spectra of Cd1−xZnxTe (x = 0.04) crystals

“…The scattering effect of Te-rich phases on the IR transmission of CZT is closely related to their size. According to Yadava et al's calculation, 11 only those Te-rich phases with dimensions smaller than 1 µm could notably affect Mie scattering while Te inclusions larger than 1 µm could not.…”

“…Free carrier absorption and the scattering of the precipitates are the major factors that can severely influence the IR transmission of CZT. 11 In n-type polar semiconductors, the simplified expression of the associated free carrier absorption coefficient α op for the polar optical phonon scattering mechanism obtained by Yadava et al is 11 α op ϭ 1.1 ϫ 10 -19 n e λ 3 (2) where n e is the free electron concentration in units of cm Ϫ3 , and λ is the wavelength of the IR ray in units of µm.…”

“…As mentioned above, the scattering of the precipitates and the absorption of the free carrier are the major factors that can significantly influence the IR transmittance of CZT. It can be assumed that the IR absorption at the wavelength of 20 µm is entirely the result of the free carrier absorption, since according to Yadava et al, 11 the Mie scattering of the precipitates only shows significant contributions up to 6 µm. Thus, the free carrier absorption coefficient α op at 20 µm is taken to be equal to the experimentally obtained absorption coefficient α exp .…”

Material quality characterization of CdZnTe substrates for HgCdTe epitaxy

“…Scattering makes a significant contribution to the transmission of IR radiation with wavelengths smaller than 6 mm (i.e., wave numbers higher than 1667 cm ÿ 1 ). 8 Thus, we can assume that for higher wavelengths the free-carrier absorption is chiefly responsible for the transmittance deterioration. Figure 6 shows that samples 4 and 5 have almost the same type of spectra with transmittances of 63% and 65%, respectively; for sample 5, both freecarrier absorption and scattering provide a small contribution to the transmittance.…”

“…By analyzing data with respect to the transmittance values at the extremes of the range of interest, we can qualitatively determine the mechanism affecting the deterioration of the infrared transmittance and ultimately the defect structures responsible for the loss of transmittance. 8 Material Quality Characterization of CdZnTe Substrates for HgCdTe Epitaxy Two mechanisms are mainly responsible for transmittance reduction: scattering effect from Te-rich phases smaller than 1 mm 8 and free-carrier absorption. The free-carrier concentration changes with the concentration of point defects.…”