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Luminescence induced by elastic and plastic deformation of II – VI semiconductors at fixed strain rates

B. P. CHANDRA1,* , R. K. GOUTAM2, V. K. CHANDRA3, R. P. PATEL1, A. K. LUKA3, R. N. BAGHEL4

Affiliation

  1. Shri Shankaracharya College of Engineering and Technology, Junwani, Bhilai (C.G.) 490020, India
  2. Department of Postgraduate Studies and Research in Physics, Rani Durgawati University, Jabalpur 482001, India
  3. Department of Physics and Computer Science, Government Nagarjuna Science College, Raipur 492010, India
  4. Department of Physics, Pt. Ravishankar Shukla University, Raipur 492010, India

Abstract

The mechanoluminescence (ML) emission during the elastic deformation of ZnS:Mn crystals occurs due to the electrostatic interaction between dislocation segments and filled electron traps, and the ML emission during the plastic deformation of IIVI semiconductors takes place due to the mechanical interaction between the moving dislocations and filled electron traps. In the elastic region, the ML intensity increases linearly with the strain or deformation time, and in this case, the saturation region could not be observed because of the beginning of plastic deformation before the start of saturation in the ML intensity. In the plastic region, initially the ML intensity also increases linearly with the strain or deformation time, and later on it attains a saturation value for large deformation. When the deformation is stopped, then at low temperature the ML intensity decreases with time whereby the decay time of ML gives the relaxation time of dislocation segments or pinning time of the dislocations. For the deformation at fast strain rate, there are two components of ML decay, in which the fast decay gives the relaxation time of dislocation segments or pinning time of dislocations, and the slow decay gives the lifetime of electrons in the shallow traps The saturation value of the ML intensity increases linearly with the strain rate and also with the density of filled electron traps in the crystals. The saturation value of ML intensity decreases with increasing temperature of the crystals because of the decreases of the luminescence efficiency and radius of interaction of dislocations with filled electron traps with increasing temperature. From the ML measurements the relaxation time of dislocation segments, pinning time of dislocations, and the lifetime of electrons in shallow traps can be determined. Expressions derived for the ML induced by elastic and plastic deformation of II-VI semiconductors at fixed strain rate, indicate that the ML intensity depends on the strain, strain rate, stress, ....

Keywords

Mechanoluminescence, Luminescence, Optical properties, II-VI semiconductors, Dislocations electron traps.

Citation

B. P. CHANDRA, R. K. GOUTAM, V. K. CHANDRA, R. P. PATEL, A. K. LUKA, R. N. BAGHEL, Luminescence induced by elastic and plastic deformation of II – VI semiconductors at fixed strain rates, Optoelectronics and Advanced Materials - Rapid Communications, 3, 11, November 2009, pp.1181-1189 (2009).

Submitted at: Sept. 15, 2009

Accepted at: Oct. 29, 2009