The influence of surface treatment, ambient gas and temperature on the reverse characteristics of alloyed silicon p-n junctions

A study has been made of the electrical characteristics of silicon alloyed p+-n diodes in a variety of ambient gases, at temperatures between 20°C and 250°C, and after several types of surface chemical treatment. Results obtained on devices before heating are interpretable in terms of accepted theory for device characteristics under the influence of channels and accumulation layers but after heating to 250°C in oxygen or nitrogen several complicating features are observed. Results indicate that heating in oxygen produces slow surface states giving rise to reverse current drifts in wet atmospheres over periods of the order of 15 minutes, while heating in nitrogen produces a lowered surface potential with resulting low-voltage surface breakdown, which suggests that nitrogen may be unsuitable as an encapsulation gas in devices designed to operate at high temperatures.