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Title: Semi insulating CdTe:Cl after elimination of inclusions and precipitates by post grown annealing

Abstract

We present in this contribution results of two-step annealing, when the CdTe:Cl doped samples are at first annealed under Cd overpressure to remove inclusions and the re-annealed under Te overpressure to restore the high resistivity state. Investigation of samples after Cd rich annealing by infrared microscope has proven, that all inclusions are removed. Also Te nano precipitates were strongly influenced by the annealing process. The resistivity of the samples after Te-rich annealing was restored to values ( ~ 108-109Ωcm). We observed, however, decrease of mobility-lifetime product of electrons from 10-3cm2/Vs to 10-4cm2/Vs. In order to understand the reason of this decrease we performed a study of point defects before and after annealing by thermoelectric effect spectroscopy. It shows a decrease of concentrations of most deep levels after two-step annealing. This behavior is completely different compared to past annealing studies, where concentration of deep levels strongly increased after annealing. The only level with an increased concentration in the current study is the midgap level (E ~ 0.8 eV). At the same time we observed increase of micro-twins in the samples investigated by transmission electron microscopy. The decrease of charge collection efficiency after two-step annealing may be therefore connected with re-arrangement ofmore » near midgap levels due to increase of concentrations of structure defects (micro twins, dislocations) that accumulate in their surroundings point defects with energy ~ 0.75 eV.« less

Authors:
; ; ; ; ; ; ; ; ;
Publication Date:
Research Org.:
BROOKHAVEN NATIONAL LABORATORY (BNL)
Sponsoring Org.:
USDOE SC OFFICE OF SCIENCE (SC)
OSTI Identifier:
1076956
Report Number(s):
BNL-99116-2013-JA
Journal ID: ISSN 1748-0221; NN2001000
DOE Contract Number:  
DE-AC02-98CH10886
Resource Type:
Journal Article
Journal Name:
Journal of Instrumentation
Additional Journal Information:
Journal Volume: 7; Journal Issue: 11; Conference: 14th International Workshop on Radiation Imaging Detectors; Figueira Da Foz, Portugal; 20120701 through 20120705; Journal ID: ISSN 1748-0221
Publisher:
Institute of Physics (IOP)
Country of Publication:
United States
Language:
English
Subject:
36 MATERIALS SCIENCE; Solid state detectors; Charge transport and multiplication in sokid media; Materials for solid-state detectors

Citation Formats

Franc, J., Belas, E., Bug?r, M., Hl?dek, P., Grill, R., Yang, G., Cavallini, A., Fraboni, B., Castaldini, A., and Assali, S. Semi insulating CdTe:Cl after elimination of inclusions and precipitates by post grown annealing. United States: N. p., 2012. Web. doi:10.1088/1748-0221/7/11/C11001.
Franc, J., Belas, E., Bug?r, M., Hl?dek, P., Grill, R., Yang, G., Cavallini, A., Fraboni, B., Castaldini, A., & Assali, S. Semi insulating CdTe:Cl after elimination of inclusions and precipitates by post grown annealing. United States. doi:10.1088/1748-0221/7/11/C11001.
Franc, J., Belas, E., Bug?r, M., Hl?dek, P., Grill, R., Yang, G., Cavallini, A., Fraboni, B., Castaldini, A., and Assali, S. Thu . "Semi insulating CdTe:Cl after elimination of inclusions and precipitates by post grown annealing". United States. doi:10.1088/1748-0221/7/11/C11001.
@article{osti_1076956,
title = {Semi insulating CdTe:Cl after elimination of inclusions and precipitates by post grown annealing},
author = {Franc, J. and Belas, E. and Bug?r, M. and Hl?dek, P. and Grill, R. and Yang, G. and Cavallini, A. and Fraboni, B. and Castaldini, A. and Assali, S.},
abstractNote = {We present in this contribution results of two-step annealing, when the CdTe:Cl doped samples are at first annealed under Cd overpressure to remove inclusions and the re-annealed under Te overpressure to restore the high resistivity state. Investigation of samples after Cd rich annealing by infrared microscope has proven, that all inclusions are removed. Also Te nano precipitates were strongly influenced by the annealing process. The resistivity of the samples after Te-rich annealing was restored to values ( ~ 108-109Ωcm). We observed, however, decrease of mobility-lifetime product of electrons from 10-3cm2/Vs to 10-4cm2/Vs. In order to understand the reason of this decrease we performed a study of point defects before and after annealing by thermoelectric effect spectroscopy. It shows a decrease of concentrations of most deep levels after two-step annealing. This behavior is completely different compared to past annealing studies, where concentration of deep levels strongly increased after annealing. The only level with an increased concentration in the current study is the midgap level (E ~ 0.8 eV). At the same time we observed increase of micro-twins in the samples investigated by transmission electron microscopy. The decrease of charge collection efficiency after two-step annealing may be therefore connected with re-arrangement of near midgap levels due to increase of concentrations of structure defects (micro twins, dislocations) that accumulate in their surroundings point defects with energy ~ 0.75 eV.},
doi = {10.1088/1748-0221/7/11/C11001},
journal = {Journal of Instrumentation},
issn = {1748-0221},
number = 11,
volume = 7,
place = {United States},
year = {2012},
month = {11}
}