A distinctive architecture design of lateral p–n type GaN ultraviolet photodetectors via a numerical simulation

Abstract

The conventionally vertical p-n type gallium nitride (GaN)-based ultraviolet (UV) photodetectors (PDs) suffer from the drawbacks of insufficient light absorption in the depletion region, thus resulting in poor carrier separation efficiency. The architecture of lateral p-n type GaN-based UV PDs has attracted much attention with applications in numerous fields due to their unique photoelectric properties. However, the potential of this type of devices has not yet been fully unlocked because of lacking a complete understanding of the design principles and working mechanisms. Here, a detailed photoelectronic model was developed to address the processes of carrier generation, transport, recombination and extraction to clarify the underlying mechanisms of the lateral p-n type UV PDs. By comparing with the vertical UV PDs, the lateral PDs show similar optical response, but higher photo-to-dark current ratio (PDCR) and responsivity when GaN is heavily doped. Moreover, it is also confirmed that the performance of the lateral p-n devices is almost independent of GaN thickness, providing significant inspiration for the development of ultra-thin UV PDs.