https://doi.org/10.15407/iopt.2023.58.128

Optoelectron. Semicond. Tech. 58, 128-135 (2023)

P.O. Gentsar, M.A. Mynaylo, L.A. Demchyna, M.V. Vuichyk, O.I.  Vlasenko

OPTICAL SPECTROSCOPY OF DETECTIVE HIGH RESISTANCE CdTe(111) MONOCRESISTORS AND SOLIDS Cd 1-x Zn x Te

Cadmium telluride is used for the manufacture of uncooled gamma radiation detectors, and solid solutions of

Cd 1-x Zn x Te (x=0.1) are used for the manufacture of X-ray and gamma radiation detectors. The study of the effect of

doping on the physical properties of semiconductors is relevant both for experimenters and for the theoretical

substantiation of physical processes. This paper presents the results of the study of optical reflection spectra in the

spectral range (0,2-1,7)  . 10 -6 m and transmittance in the region of the fundamental optical transition E 0 of high-resistivity

CdTe single crystals of (111) orientation with resistivity ρ = (2÷5)·10 9  Ohm∙cm doped with chlorine, as well as solid

solutions of Cd 1-x Zn x Te  (x = 0.1) with resistivity ρ = (5 ÷30)∙10 9  Ohm∙cm. Since the optical reflection coefficient R = f

(λ) is related to the optical transmittance T = f (λ) and absorption D = f (λ) by the ratio R+T+D=1 (with the light

(electromagnetic) wave scattering in the studied samples not taken into account), the absorption spectra D=1-(R+T)

versus the light (electromagnetic) wavelength λ were also constructed in this work. It is determined that the energy of

the fundamental optical transition E 0 of the studied materials at T = 300 K is as follows: for CdTe - 1.44 eV; and for

Cd 1-х Zn х Te  (x = 0.1) - 1.5 eV. The energy relaxation time of free charge carriers τ for p-CdTe (111) single crystals and

Cd 1-х Zn х Te  (x = 0.1) solid solutions was estimated to be 1.343-10 -14 s and 0,878·10 -14  s, respectively. The effective

"optical" mobility for single crystals of p-CdTe (111) and solid solutions of Cd 1-х Zn х Te (x = 0.1) is 274 . 10 -4 ; 179,5 .

10 -4 , respectively. It has been shown that the investigated crystals are of high (detector) quality, which is crucial for

the manufacture of highly sensitive and high-resolution ionising radiation sensors. The practical value of the obtained

results lies in the determination of electronic and physical parameters of technically important semiconductors CdTe

and Cd 1-х Zn х Te  (x=0.1).

Keywords: reflection, transmission, absorption, CdTe, Cd 1-x Zn x Te.