High Inverse Voltage Germanium Rectifiers

Abstract

Rectifying current-voltage characteristics going up to several hundred volts inverse have been observed in metal-germanium point contact rectifiers. A reproducible negative differential resistance region occurs in the inverse characteristic. Certain impurities are desirable in producing high voltage material. Surface treatment, e.g., by etching, is very important. The metal used as a whisker has little effect. Increasing the force of contact increases greatly the current of low voltages but has less effect on the high voltage curve. Pronounced improvement of rectification can be effected by treatment of the contact with large currents. Variation with temperature is very marked, especially for crystals of large inverse resistance; the variation of the inverse peak with temperature indicates that contact heating is responsible for the negative resistance. Time lags in the inverse negative resistance region of the order of 10−5 second occur. When contact is made between two Ge crystals, typical inverse characteristics are observed in both directions. Photoelectric effects are observed and indicate that the barrier thickness is greater the higher the inverse peak voltage.