AU AND AG ELECTRICAL CONTACTS TO P-ZNSE

The reverse bias break-down voltage and resistance of Au and Ag contacts sputter deposited on nitrogen doped p-type ZnSe, having free hole concentrations in the low to mid 10(17) cm(-3) range, have been studied. Samples were heat treated over the range of 150-400 degrees C for times of 15-45 min. The minimum break-down voltage for the Au contacts (3.0 V) was found to occur following heat treatments at 350-400 degrees C for 30 min and for Ag contacts (2.3 V) following heat treatments at 150 degrees C for 45 min. Secondary ion mass spectrometry and Auger electron spectroscopy were used to identify changes in the contacts induced by heat treatments. No evidence was found for the formation of new interfacial compounds, but Au diffused into the ZnSe at T > 350 degrees C. The data suggest that conduction through the Au/ZnSe contacts was dominated by avalanche breakdown assisted by deep acceptor levels formed by the diffusion of Au into the ZnSe. The results from the Ag contacts suggest that interfacial O forms a highly doped region in the ZnSe leading to conduction dominated by field emission currents.