The effect of deformation phenomena on optical and photoelectric processes in cadmium telluride single crystals

Ihor S. Virt 1Volodymyr Popovych 1Ivan Kurilo 2Igor Rudyi 2

1. Drogobych State Pedagogical University, Ivan Franko st., 24, Drogobych 82100, Ukraine
2. Lviv Polytechnic National University, 12 Bandera, Lviv 79013, Ukraine

Abstract

We studied the changing of the CdTe single crystalline samples properties caused by purposive introducing of fresh dislocations by means of uniaxial compression under constant load as well as by indentation. The dislocation density (DD) increased by more than two order of magnitude after the deformation. The temperature dependences of dark conductivity in the region of 100-300 K correspond to the activation energy of Ei = 82 meV both for initial and deformed samples but the carriers concentrations increase with DD rising. The RT carriers lifetimes determined from the decaying parts of transient photoconductivity signals decreased in 2-5 times after the deformations. The shallow level Et = 11 meV participates in the relaxation processes of the initial samples. A recombination through deep centers dominates in deformed crystals indicating that there the overcompensation took place. The analisys of the photoconductivity kinetics revealed the increase of the surface recombination centers concentration and persistent photoconductivity in the last case. The values of the transmission cut-off energy point out the optical band gap narrowing up to 8% in deformed samples. The optical absorption edges become more broadened and their temperature shifts become a little smaller with the increasing of the DD. The last facts are explained by the disordering processes and deformational goffering of energy gaps.

 

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Presentation: Poster at E-MRS Fall Meeting 2006, Symposium F, by Ihor S. Virt
See On-line Journal of E-MRS Fall Meeting 2006

Submitted: 2006-05-12 18:36
Revised:   2009-06-07 00:44