Effects of persistent photoconductivity on the characteristic performance of an AlGaN/GaN heterostructure ultraviolet detector

Photocurrent (PC) transient characteristics of an AlGaN/GaN heterostructure UV detector have been studied. We observed that the PC transients of the AlGaN/GaN heterostructure depended strongly an its initial conditions. Under a pulsed laser excitation, the PC responsivity, dark current level, and decay time constant all increased progressively with the number of successive excitation pulses and eventually saturated at constant values after about 30 pulsed laser exposures. Our results indicate that the observed PC transient characteristics are directly correlated with the effect of persistent photoconductivity in the two-dimensional electron gas region caused by deep level impurities and can have a significant influence on the performance of the UV photodetectors based on AlGaN/GaN heterostructures. (C) 1998 American Institute of Physics.