Current-voltage characteristics of p-Ge/n-CdS heterojunction diodes

Abstract

The current‐voltage characteristics of p‐Ge/n‐CdS heterojunction diodes have been studied for a wide range of diodes fabricated under different CdS film growth conditions. It has been found that under certain growth conditions the diodes possess two resistance states: Switching from the high‐ to low‐resistance state occurs with a small reverse‐bias voltage, while switching from the low‐ to high‐resistance state occurs with a small forward‐bias voltage. Measurements have been carried out on the junction capacitance, and it has been found that the capacitance increases when the diode is switched to the low‐resistance state and reverts to its initial value when the diode is switched back to the high‐resistance state. It is concluded that the two resistance states of the diode are associated with a junction phenomenon and not with some change in the physical state of the n‐type film. A prerequisite for this behavior would appear to be that the dielectric relaxation time should be greater than the diffusion lifetime.