A PMT-like high gain avalanche photodiode based on GaN/AlN periodical stacked structure

摘要

Avalanche photodiode (APD) has been intensively investigated as a promisingcandidate to replace photomultiplier tubes (PMT) for weak light detection.However, in conventional APDs, a large portion of carrier energy drawn from theelectric field is thermalized, and the multiplication efficiencies of electronand hole are low and close. In order to achieve high gain, the device shouldwork under breakdown bias, where carrier multiplication proceedsbi-directionally to form a positive feedback multiplication circle. However,breakdown is hard to control, in practice, APDs should work under Geiger modeas a compromise between sustainable detection and high gain. The complexity ofsystem seriously restricts the application. Here, we demonstrate an avalanchephotodiode holding high gain without breakdown, which means no quenchingcircuit is needed for sustainable detection. The device is based on a GaN/AlNperiodically-stacked-structure (PSS), wherein electron holds much higherefficiency than hole to draw energy from the electric field, and avalanchehappens uni-directionally with high efficiency. and a recorded high gain (10^4)tested under constant bias is obtained in a prototype device, wherein thestable gain can be determined by the periodicity of the GaN/AlN PSS. This worknot only brings a new light into avalanche multiplication mechanism, but alsopaves a technological path with high commercial value to realize highlysensitive avalanche devices working under constant bias like PMT.