InGaAs/InP negative feedback avalanche diodes (NFADs)

In recent years substantial effort has been made in material growth, device design and fabrication, and driving circuitry to improve the performance of InGaAs/InP single photon avalanche diodes (SPADs) operated in Geiger mode. Despite these efforts, InGaAs/InP SPADs are constrained by certain performance limitations due to the inherent positive feedback involved in the avalanche process. With the goal of overcoming some of these performance limitations, we have successfully designed and implemented thin film resistors monolithically integrated with InGaAs/InP SPADs to provide a negative feedback mechanism to regulate the avalanche sizes. The monolithic integration scheme ensures very small parasitic effects, results in fast quenching of avalanches, and allows for wafer-level integration which facilitates the fabrication of array structures. We will discuss the design and operation of NFAD devices and performance characterization of these devices. Basic characteristics of NFADs such as pulse response, quenching and recovery dynamics will be described. We will also present device performance parameters such as photon detection efficiency (PDE), dark count rate (DCR) and afterpulsing probability (Pap). InGaAs/InP negative feedback avalanche diodes with different device sizes and quenching resistances have been designed and fabricated. Devices with ~10% PDE and acceptable Pap has been realized, which provides a simple, practical solution for certain photon-counting applications.