Experimental investigation of the transient behavior of gold—Germanium surface barriers

Following the application of a current pulse to a semiconductor diode, a transient voltage appears which is caused by deviations in carrier concentrations near the barrier. The high-frequency capabilities of a diode are intimately related to the decay time of this transient voltage, which is treated herein for a variety of experimental conditions. The open circuit voltage following a small amplitude impulse current was investigated with different values of fixed bias. The recovery time was observed to decrease with increasing forward bias, and the voltage was seen to decay exponentially with time given sufficiently forward bias. The effect of the duration of the injection upon the voltage decay was also investigated. It was noted that there was a rapid initial decay which was faster with shorter injection, and a final exponential decay which was insensitive to the duration of the current pulse; however, it was dependent upon the bulk lifetime of the material. The influence of the surface barrier itself upon the transient behavior was also investigated. In general the recovery time was found to be faster with decreasing injection ratio. The open-circuit voltage following a large amplitude current pulse was investigated using specimens with near unity injection ratios. The final voltage decreased linearly with time, the slope being determined by the bulk lifetime.