Emerging semiconductor nanostructure materials for single-photon avalanche diodes

Abstract

Detecting of light at the single photon level has a far-reaching impact that enables a broad range of applications. In sensing, advances in single-photon detection enable low light applications such as night-time operation, rapid satellite communication, and long-range three-dimensional imaging. In biomedical engineering, advancing single-photon detection technologies positively impacts patient care through important applications like singlet oxygen detection for dose monitoring in cancer treatment. In industry, impacts are made on state-of-the-art technologies like quantum communication which relies on the efficient detection of light at the fundamental limit. While the high impact of single-photon detection technologies is clear, the potential for improvement and challenges faced by prominent single-photon detection technologies remains. Superconducting single-photon detectors push the bounds of performance, but their high cost and lack of portability limits their prospect for far reaching applicability. Single-photon avalanche diodes (SPADs) are a promising alternative which can be made portable, absent of the need for cryogenic cooling, but they generally lack the performance of superconducting detectors. The materials in SPAD designs dictate operation, and conventional materials implemented being defined according to intrinsic material properties, limits SPAD performance. However, new classes of advanced materials are being realized which exhibit modified electromagnetic properties from the engineered arrangement of subwavelength structural units and low-dimensional properties. Such materials include metamaterials and low-dimensional materials, and they have been shown to enhance optoelectrical properties that are critical to avalanche photodiodes, like rapid photo response, enhanced absorption, and reduced dark current. In this work, the application of such advanced materials in SPADs is explored. Tapered nanowires and nanowire arrays are optimized for enhanced absorption and shown experimentally at room temperature to demonstrate high speed near-unity absorptance response at the single-photon level. In the metamaterial and nanowire devices, the gain and timing jitter are shown to be significantly improved over conventional bulk-based designs. Furthermore, the modelling of metamaterials in a SPAD device design and its operation with external single-photon detection circuitry is studied. The analysis is further shown to extend down to single nanowire devices which offers an elegant approach for integrated photonic circuits.