Simulations of Nanoscale Room Temperature Waveguide-Coupled Single-Photon Avalanche Detectors for Silicon Photonic Sensing and Quantum Applications

Photonic qubits can represent an ideal choice in quantum information science since photons travel at the speed of light and interact weakly with the environment over long distances. In this context, technological platforms allowing the development and implementation of chip-scale integrated photonics represent a possible solution toward scalable quantum networking schemes. However, at present, most examples of integrated quantum photonics still require the coupling of light to external photodetectors operating at very low temperatures. In this paper, we demonstrate that the GeSn/Si-in-SOI technological platform can be a good candidate to realize integrated single-photon avalanche detectors (SPADs), operating at room temperature. Thus, we report the design and simulation of waveguide-based SPADs for operation at 1550 and 2000 nm wavelengths. We calculate the breakdown voltage, the dark count rate (DCR), the single photon detection efficiency (SPDE), the noise equivalent power (NEP), the dark count, and the afterpulsing probabilities by simulating the avalanche process and the statistical features in a self-consistent way. The PIPIN SPAD performance parameters are estimated as a function of the GeSn's threading dislocation density and of the temperature. We also demonstrate that for operation at 1550 and 2000 nm wavelengths with the 220 nm GeSn separate absorber film centered in the 250 nm high Si waveguide end, it is possible to cover a number of applications at room or near room temperature, ranging from ultrasensitive LIDAR to quantum communications, metrology, sensing, and key distribution.