Photoplastic Effect in Narrow-Gap Mercury Chalcogenide Crystals

Abstract

The paper elucidates the peculiarities of photoplasticization effect (PPE) occurring in narrow-gap crystals of mercury chalcogenides illuminated by white light during the process of uniaxial deformation. As found, the irradiation has an influence on the plastic deformation in narrow-gap Cd x Hg 1 x Te crystals. Negative photoplasticization effect (NPPE) described here is concerned with reducing of plastic stress fluidity under white-light irradiation during plastic deformation of crystals at a constant rate. As found, in contrary to wide-bandgap crystals of the II-VI groups exhibiting positive PPE, NPPE observed in Cd x Hg 1 x Te occurs without internal photoeffect. A model explaining the nature of NPPE relies on a decreasing of positive charge in a native oxide layer at the surface of crystal. Charge decreasing reduces potential barrier for exiting on surface of dislocations generated by near-surface sources during dynamical loading. As a result, the level of fluidity stress in the deformed crystal is reduced.

Regularities of macroplastic deformation of narrow-band single crystals of CdxHg 1-xTe solid solutions

“…Nature of NPPE in narrow bandgap CdHgTe crystals is related to the reduction in mechanical stress under the influence of light due to the decrease of the embedded positive charge at interphase 'intrinsic oxide -semiconductor" boundary [8]. This is accompanied by the decrease in the deformation barrier EMU for the exit of generated dislocations on the surface of the crystal, resulting in reduced level of fluidity stress in the crystal deformed at a constant rate under irradiation.…”