Cooling-stimulated electron emission and anomalous changes in the conductivity of CdS crystal faces

B.V.Pavlyk, B.Z.Cybulyak, Ya.M.Goryn', I.V.Kozak


Ivan Franko Lviv State University, 50 Dragomanov St., 290005 Lviv, Ukraine

Received May 22, 1998

The effect of electron emission from basal S (000bar1) and Cd (0001) faces of CdS crystals when being cooled down to the liquid nitrogen temperature has been revealed. Anomalous temperature relationships of the surface conductivity of those faces have been studied both in high-resistance (ne<<108 cm-3) and low-resistance (n~1014 cm-3) crystals. The correlation of results obtained prior to and after the heat treatment of samples allowed to propose a mechanism of the conductive layer formation and electron emission in the course of cooling. The interstitial excess Cd is supposed to be displaced towards the (0001) crystal face in the band bending field. Metastable defects are formed therewith in the crystal near-surface layer and re-built as the temperature lowers forming the low-resistance conductive layer. The crystal pyrofield stimulates the emission of free electrons into vacuum without preceding excitation.

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