Abstract
The electrical properties of metal-CdTe contacts have been measured for a diverse group of 18 metals by using current-voltage and capacitance-voltage techniques. The contacts were formed by metal evaporation onto chemically etched surfaces of n-CdTe single crystals. A large number of metals yield a barrier height of 0.72+or-0.03 V, independent of the work function of the metal. Mn, Cr and V were different, producing ohmic or very low barriers. The nature of the CdTe(110) surfaces produced by chemical etching using bromine in methanol was studied by an X-ray photo-emission technique. The authors have also carried out a detailed investigation into the microscopic interactions at selected interfaces by soft X-ray photo-emission using a synchrotron radiation source. Detailed comparisons of the microscopic interaction of Ag and Mn with the oxidised surfaces, using photo-emission are reported. In contrast to the behaviour of Ag, the Mn overlayer reduces completely the CdTe native oxide layer, leading to low-barrier contacts. It has been found that the bulk thermodynamic data provide an approximate description of the interface reactivity for most of the systems studied.
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