Doping studies in MOVPE-grown CdxHg1-xTe

Abstract

In two recent review papers on metal organic vapour phase epitaxy (MOVPE) of cadmium mercury telluride (CMT) particular emphasis was placed on the crucial importance of doping studies to the realization of future device structures Irvine et al. (1991) and Tribowet (1991). If the full potential of MOVPE growth of CMT is to be realized then extrinsic doping of heterostructures is required. If the doping and composition junctions can be grown with the correct degree of grading then this will create the potential for the production of device structures leading to either improved performance and/or increased operating temperatures. This papers reviews published doping studies and also presents some recent results on both acceptor and donor doping studies carried out by the authors. In the latter studies, interdiffused multilayer process (IMP) growth of CMT has been performed at approximately=360 degrees C using dimethyl cadmium (DMC) and di-isopropyl tellurium (DIPT) as the MO precursors while the Hg overpressure was provided by a heated elemental source. Alternative acceptor doping sources to arsine have been investigated including phosphine, triphenyl arsenic, and phenyl arsenic of which the latter appears to be most suitable. Iodine has continued to show the donor dopant potential in CMT that it exhibited with higher-temperature ( approximately=400 degrees C) MOVPE growth using di-ethyl tellurium (DET). Characterization of fully doped structures is described.