Optical characteristics of a superlattice avalanche photodiode

Abstract

Avalanche photodiodes using III-V materials are suitable for use in long distance fiber optic communication systems due to their faster speed of response and high gain. The superlattice APD is expected to be far more attractive than the conventional APD for their better noise performance. Theoretical studies have been carried out on the photoresponse characteristics of an AlxGa1-xAs/GaAs superlattice p+-i-n+ structure. It is observed that for a particular d.c. multiplication factor the normalised gain of the device remains constant with frequency and falls steadily after a certain frequency. The band width of the response curve increases with decrease in d.c. multiplication factor. Furthermore, the output current of the superlattice structure increases with the increase in optical power. The device also shows a good percentage of quantum efficiency. © 1987.