Method for obtaining optically clear, high resistivity ii-vi, iii-v, and

Abstract

Desired conductivity type and carrier concentration in the Group II-VI, III-V, and IV-VI compounds in which at least one constituent is volatile is obtained by varying the partial pressure of one of the volatile constituents with respect to the compound solid, which is then controllably cooled while simultaneously changing the component pressure to maintain the compound within the high resistivity area of its phase diagram. For example, donor doped cadmium telluride is maintained at a temperature range of about 1000.degree. C. at 0.9 atmospheres in the constituent atmosphere to obtain high resistivity (up to 10.sup.9 ohm-cm.) and then slow-cooled to a preferred temperature of 700.degree. C. or lower in the high resistivity region and/or between the stoichiometric line and its dope line, and then into the high resistivity region but above its minimum pressure line where the compound begins to sublime congruently, followed by removal of the material from the furnace. The invention has been reported in Materials Research Bulletin, Vol. 8, pp. 523-532, 1973, Pergamon Press, Inc.