Search for content and authors
 

High temperature defect equilibrium in ZnS:Cu single crystals

Kalju Lott 1Svetlana Shinkarenko 1Leo Türn 1Tiit Nirk 1Andres Öpik 1Urve Kallavus 2Elena Gorokhova 3Andrei Grebennik 4Anatoli Vishnjakov 4

1. Tallinn University of Technology (TUT), Ehitajate tee 5, Tallinn 19086, Estonia
2. Tallinn University of Technology,Centre for Materials Research (TUT), Ehitajate tee 5, Tallinn 19086, Estonia
3. S.I. Vavilov State Optical Institute, St-Petersburg, Russian Federation
4. D.I.Mendeleyev University of Chemical Technology of Russia (MUCTR), Miusskaya Sq., Moscow 125047, Russian Federation

Abstract

This report presents high temperature defect equilibrium (HTDE) model for Cu-doped ZnS crystals based on high temperature electrical conductivity (HTEC) measurements. HTEC data were obtained under defined conditions of component vapour pressure and of sample temperature. The appearance of different slopes on HTEC isotherms can be explained by a two-carrier conduction mechanism involving electrons and holes. All HTEC isotherms investigated can be divided into four regions. The high Zn vapor pressure region characterized by positive HTEC isotherm slope caused by native donors changes into negative slope caused by the decrease of Cu solubility. The slope of HTEC isotherm change   negative again at low Zn vapor pressures. It is caused by increasing part of holes in bipolar conductivity. Analogous behavior of HTEC isotherms is observed also at low sulphur vapor pressures. The result is surprisingly similar to HTDE models for Ag-doped CdS [1] and for doped CdTe [2]. The method for solving the system of quasi-chemical reactions without approximation [3] was used. Our experimental data can be explained only by the inclusion of abnormal site occupation i.e. by antistructural disorder. This involves the occurance of sulfur at a zinc lattice, which must be expected to be a donor. Association of copper with this antistructure defect occurs also. Antistructure disorder disappears with increasing of Zn vapor pressure. Preliminary HTDE isotherms and isobars containing antistructure disorder and Cu solubility limitation are proposed.

References:

[1] H.R. Vydyanath, F.A. Kröger J. Phys. Chem. Solids 36, 509 (1975)

[2] R. Grill, J. Franc, P. Hoschl, I. Turkevych, E. Belas, P. Moravec, M. Fiederle, K.W. Benz IEEE Transactions on Nuclear Science 49, (3, Pt. 2), 1270 (2002)

[3] K. Lott, L. Türn  J. Crystal Growth 197, 493 (1999)

 

Legal notice
  • Legal notice:
 

Related papers

Presentation: Poster at E-MRS Fall Meeting 2009, Symposium C, by Kalju Lott
See On-line Journal of E-MRS Fall Meeting 2009

Submitted: 2009-04-23 20:16
Revised:   2009-06-07 00:48