p-type doping efficiency in CdTe: Influence of second phase formation

Published: January 29, 2018

Author(s)

Jedidiah J. McCoy, Santosh K. Swain, David R. Diercks, Brian Gorman, Kelvin G. Lynn, John R. Sieber

Abstract

Cadmium Telluride (CdTe) high purity, bulk crystals doped with phosphorus have been grown via vertical Bridgman melt growth technique to understand and improve dopant solubility and activation. Large net carrier densities have been reproducibly obtained from as-grown ingots, indicating successful incorporation of dopants into the lattice. However, carrier density values are orders of magnitude lower than the upper range of theoretical solubility, 1018/cm3 to 1019/cm3 [1], despite comparable dopant charge densities. Growth conditions, such as melt stoichiometry and post growth cooling, are shown to have significant impacts on dopant solubility. We theorize that a portion of dopant becomes incorporated into second phase defects as compounds of cadmium and phosphorous, such as cadmium phosphide, which inhibits dopant solubility into the lattice and limits maximum attainable net carrier density in bulk crystals. Here, we present an extensive study on the characteristics of these second phase defects in relation to their composition and formation kinetics, while providing a pathway to minimize their formation and enhance solubility.
Citation: Journal of Applied Physics
Volume: 123
Issue: 16
Pub Type: Journals

Keywords

CdTe, Bridgman growth, second phase, p-type, microXRF, SEM-EDS, active site density
Created January 29, 2018, Updated January 31, 2018