Factors Affecting Reliability of Alloy Junction Transistors

Oxygen and water vapor, when individually in contact with the transistor surface, have been found to cause substantial and generally opposite changes in the characteristics of germanium alloy junction transistors. These changes, however, are reversible: by means of vacuum baking a reproducible set of characteristics can be repeatedly reestablished after water vapor or oxygen has caused a large change in the characteristics. Very pure forms of other ordinary gases, such as hydrogen, nitrogen, and helium, are found to have no effect on these transistors. Very nearly ideal time stability of characteristics can be obtained, even under severe aging conditions, when water vapor and oxygen are completely removed and permanently excluded from the transistor surface, although under some circumstances a very pure atmosphere of oxygen (or air) may be desirable for the p-n-p transistor.