NONMETAL IN-SITU AND EX-SITU OHMIC CONTACTS TO N-ZNSE

The formation of ohmic contacts between indium tin oxide (ITO) and MBE -grown n-ZnSe layers has been investigated using x-ray photoelectron s pectroscopy (XPS) and currrent voltage (I-V) techniques. In contrast t o metal-ZnSe contacts, ohmic behaviour is found for ITO contacts made in situ to as-grown n-ZnSe layers as well as contacts made ex situ to oxidized layers. It is possible to form ohmic contacts for ZnSe doping levels in the range of n = 2 x 10(17) to 8 x 10(18) cm(-3) with conta ct resistances as low as R-c = 9 x 10(-3) Omega cm(2). By probing the ITO/ZnSe interface with XPS a mechanism for the contact formation is p roposed.