Influence of laser radiation on photoluminescence of CdTe

Generation of the A-centres at the surface of CdTe(Cl) by YAG:Nd laser radiation

An influence of laser-induced stress and shock waves on photoelectric properties of epitaxial n- (CMT) films with a cellular structure was studied. Irradiation of CMT films with nanosecond ruby laser pulses resulted in a modification of photoconductivity spectra and an increase in the photosensitivity because of segregation of electrically active point defects at the cell boundaries (acting as sinks) and also because of changes in their electron states as a result of action of the laser-generated stress and shock waves. Using the calculations of the temperature of the samples, the depth of shock wave formation and the amplitude of shock wave at laser irradiation, it was established that the strongest photosensitization of CMT took place in deep-seated layers where the shock wave was formed. This deduction was confirmed by an increase in the photosensitivity of purpose-designed samples coated with copper foil in such a way as to exclude the photo- and thermal effects under laser irradiation of CMT solid solutions.

https://iopscience.iop.org/article/10.1088/0268-1242/13/11/012/pdf

Role of laser-induced stress and shock waves in modification of the photoconductivity of films

This work deals with the effect of Cu doping on thermal stability of the structural properties of
Y-stabilized ZrO2 nanopowders and dopants’ spatial distribution. The powders were synthesized by a co-precipitation technique, calcinated at Tc = 500–1100 °C during 2 h and studied by x-ray diffraction (XRD) and transmission electron microscopy. Calcination at Tc = 500 °C results in the formation of ZrO2 nanocrystals with tetragonal phase predominantly. The shifts of XRD peak positions of Cu-doped powders to larger angles in comparison with those of Cu-free ones testify to the Cu presence inside nanocrystals. The Tc increase results in two main processes: (i) the nonmonotonic shift of XRD peak positions and (ii) the phase transformation (tetragonal to cubic and both of them to monoclinic). This observation was explained by, at first, Cu atoms incorporation into the nanocrystal volume from the surface complexes (Tc = 500–700 °C) and then their outward diffusion followed by the formation of crystalline CuO (Tc > 700 °C). Phase transformation sets in at Tc = 700 °C, when monoclinic phase appears. Its contribution rises till Tc = 1000 °C. The mechanism of monoclinic phase formation is supposed to be consisted of the out-diffusion of interstitial Cu ions due to their shift from lattice sites. This promotes an appearance of the channels for Y out-diffusion via cation vacancies and results in phase transformation. The sintering process stimulated by CuO formation is proposed to be responsible for appearance of cubic phase at 1000–1100 °C.

/pdf/thermo-stimulated-evolution-of-crystalline-structure-and-56zykwrrnd.pdf

Thermo-stimulated evolution of crystalline structure and dopant distribution in Cu-doped Y-stabilized ZrO 2 nanopowders

Photoluminescence spectra of CdTe:Cl crystals were measured at 5 K before and after irradiation by the second harmonic of a YAG:Nd laser. It was found that the Huang–Rhys factor for donor–acceptor pair (DAP) recombination increases after irradiation with laser power above the CdTe melting point which is explained by a decrease of the DAP concentration due to Cd evaporation and to the presence of the thermogradient effect.

Influence of powerful laser irradiation on impurity-defect structure of CdTe detector material

Equilibrium conductivity and photoconductivity (PC) of MgxCd1−xTe (T = 300 K) and the PC and photomagnetic effect (PME) of CdxHg1−xTe (T = 77 K) solid solutions (SS) before and after irradiation with ruby laser pulses in the Q-switched mode are analyzed. Laser irradiation is shown to increase the forbidden gap width and to change the stoichiometric composition in the subsurface region of the SS. In n-type MgxCd1−xTe crystals a donor-enriched layer is formed and a Te film appears on the surface; in n-type CdxHg1−xTe crystals a conductivity-type inversion occurs and a built-in p–n junction arises under the action of laser emission pulses.



[Russian Text Ignored].

Surface States of Laser-Irradiated Cadmium- and Tellurium-Containing Solid Solutions of II-VI Compounds

The influence of irradiation with ruby laser emission pulses of 2 × 10−8 s in duration on electrical, photoelectrical, and luminescent properties of single crystals of ZnxCd1−xSe solid solutions (SS) is investigated. An increase of the conductivity and photosensitivity in irradiated samples is observed, which is explained by the formation of r-centres, which are metal vacancies counterbalanced by shallow donor centres. Also, a layer with a wider forbidden gap forms in the subsurface region of ZnxCd1−xSe SS crystals after irradiation. The composition changes by 3 to 5% towards an increase of x.



[Russian text Ignored.]

P. E. Mozol

Papers

Surface States of Laser-Irradiated Cadmium- and Tellurium-Containing Solid Solutions of II-VI Compounds

Laser‐Induced Defect Formation in ZnxCd1−xSe Solid Solutions and Its Influence on Electrophysical Properties

Influence of dislocations generated by laser radiation on electrophysical properties and luminescence of p-type CdTe