EVIDENCE FOR THERMODYNAMICALLY STABLE P N JUNCTION, FORMED BY AG DOPING OF (HG,CD)TE/

A p-n junction is a stable situation for electronic carriers, but not for those dopants that are the cause of the junction. Thus the junctio n is stabilized only kinetically against equilibration of the dopant c oncentrations due to the electrical and chemical potential gradients t hat reign in the depletion regions that are associated with the juncti on. The situation changes, though, when a dopant can be present in two forms, with opposite effective charges, with the majority form being responsible for doping and the minority one for drifting. Then the ele ctrical potential gradient can actually stabilize the junction. Ag, wh ich acts as an acceptor in (Hg,Cd)Te, is an example of such a dopant. Silver creates a p-n junction in Cd-rich n-(Hg,Cd)Te. We show that thi s junction is capable of restoring itself after being smeared out by s mall electrical or thermal perturbations. This behaviour suggests that we have a thermodynamically, rather than a kinetically stabilized jun ction. It indicates that Ag dissolution in MCT strongly deviates from ideal behaviour. Reasons for this non-ideality are suggested.