SEMICONDUCTIVITY OF CDS AS A FUNCTION OF S-VAPOR PRESSURE DURING HEAT TREATMENT BETWEEN 500 DEGREES AND 700 DEGREES C

The dark conductivity of CdS as a function of the sulfur vapor pressure is investigated during heat treatment in a temperature range 500° < T < 700° C. The pressure dependence follows j ∼ pS -1 m with m = lx, l being the average number of sulfur atoms per sulfur molecule in the gas phase. For 500° < T < 525° C, x = 3, for 525° < T < 630° C, x = 1 and for 630° < T < 700° C, x = 3. These results are explained by thermodynamic disorder and a Cd-rich nonstoichiometric equilibrium below 525° C. Schottky-Wagner disorder most probably is dominant above 525° C. The thermal energy of doubly ionizing a sulfur vacancy is Ec - EVS = 0.48 eV. © 1969.