COPPER OUTDIFFUSION FROM CDZNTE SUBSTRATES AND ITS EFFECT ON THE PROPERTIES OF METALORGANIC CHEMICAL-VAPOR DEPOSITION-GROWN HGCDTE

We report that HgCdTe (MCT) epilayers grown by metalorganic chemical v apor deposition can be doped by copper outdiffusing from CdZnTe substr ates. The copper content in the substrates was determined by the choic e of the purity of the starting raw materials. Copper diffusion could be controlled by adjusting the tellurium precipitate density in the su bstrates. Growing on substrates with a high concentration of tellurium precipitates resulted in low doped MCT epilayers whereas a high coppe r concentration was found in MCT grown on substrates with a lower conc entration of tellurium precipitates. A mechanism whereby tellurium pre cipitates getter copper during the post-growth cooldown of CdZnTe boul es and trap copper in the substrates is proposed.