Extended Wavelength Ge-on-Si Single-photon Avalanche Diode Detectors

This is a PhD research project in Physics. Single--photon detectors are the key components behind many of the new and emerging photonic technologies. Single--photon detection at visible and near infrared wavelengths (in the range 400 to 1060 nm) based on silicon is a relatively mature technology with several efficient devices commercially available but single-photon detectors for longer wavelengths are still largely experimental. The inclusion of germanium absorber layers gives the opportunity to extend the wavelength range to greater than 1550nm wavelength fpr compatibility with low loss optical fibre windows. Such detectors are capable of detecting photons with wavelengths that lie in certain atmospheric transmission windows, as well as infrared gas absorption features, notably those of greenhouse gas. This PhD will examine the incorporation of Sn into the Ge absorber in order to extend the wavelength range to 2000nm wavelength.