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Calculation of radiation defect profiles in CMT subjected to high power laser beams

Alexander V. Voitsekhovskii 1Mikhail Y. Leonov Sergey A. Shulga 

1. Tomsk State University (TSU), Lenina, 36, Tomsk 634050, Russian Federation

Abstract

At present time the development of infrared photo detectors with the use of the technique of high power radiation is an important branch of modern optoelectronics. Thus the major task of this research is to analyze theĀ  influence of intensive laser pulses on physicochemical properties of semiconductor crystals. As the object of study a semiconductor material, mercury cadmium telluride or MCT, is chosen. It can vary its spectral characteristics in wide range by changing molar percentage.

Improvement of a physico-mathematical model for radiation-induced defect formation in MCT under shot laser pulse influence was made. This model includes heat conduction equation, wave equation, the set of diffusion and complex formation equations for each type of radiation defects and neutrality equation. A function describing the generation of primary defects is built in such a way, that the process of defect formation occurs at the excess of melting temperature.

Heating patterns, distributions of temperature gradient and dynamic stresses which maxima are reached in near - surface area, are obtained.

Spatial profiles of the charge carrier concentration are calculated varying relations of interstitial and vacancy diffuse coefficients of mercury atoms, recombination coefficients of primary defects, and time constants of complex formation. Thus if the diffusion coefficient of interstitial atoms is sufficiently large their profiles will move into the sample and form complexes, increasing electron concentration. It is possible to observe inversion of conductivity type owing to the intensive generation of vacancy or interstitial atom complexes changing lifetime of primary radiation-induced defects. Variation of mutual recombination coefficient of vacancies and interstitial atoms has an effect on concentration profile of electrons in case of comparable diffusion rates of vacancies and interstitial atoms.

The comparison of calculation results with experimental data is made and their agreement is shown.
 

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Related papers

Presentation: Poster at E-MRS Fall Meeting 2009, Symposium D, by Mikhail Y. Leonov
See On-line Journal of E-MRS Fall Meeting 2009

Submitted: 2009-05-10 14:04
Revised:   2009-08-13 17:32