In recent years, significant progress has been made in InP-based Geiger-mode single photon avalanche diodes (SPADs), and a variety of circuits for enabling Geiger-mode operation have been proposed and demonstrated. However, due to the inherent positive feedback of the impact ionization avalanche process, Geiger-mode SPADs are constrained by certain performance limitations, particularly with regard to counting rate and the inability to resolve photon number. To overcome some of the performance limitations of regular SPADs, we have developed negative feedback avalanche diodes (NFADs) that employ a negative feedback mechanism to regulate the avalanche process. The NFAD fabrication process is based on the design platform we use to achieve state-of-the-art performance SPADs and is very flexible. The operation of NFAD devices is also very simple, with only a direct current (DC) bias being required. Various discrete devices and matrices composed of different elements have been designed, fabricated, and characterized. For discrete devices, ∼10% photon detection efficiency has been realized consistent with acceptable afterpulsing probability. The negative feedback mechanism significantly improves the uniformity of the output pulse heights and avalanche charge per detection event, resulting in a low “charge excess noise” factor. When configured in a matrix format, the NFAD devices were demonstrated to have the ability to resolve photon number and work effectively as solid-state photomultipliers (SSPMs) in the shortwave infrared (SWIR) region. The InGaAs/InP NFAD SSPMs have the potential to replace photomultiplier tubes and provide a solid-state solution in applications where the requirement for single-photon sensitivity in the SWIR region beyond ∼0.9 μm cannot be met by silicon photomultipliers. The NFAD devices have been used in various quantum optics and quantum key distribution applications and demonstrated an excellent performance.