CORDIS

µSPIRE aims at developing a key enabling technology and processing that will empower the integration on silicon of active devices, using many different semiconductor heterostructures based on materials such as Ge, GaAs and AlGaAs. In fact, many electronic and optoelectronic devices will benefit from µSPIRE fabrication technology, which provides a high degree of flexibility in the integration of dissimilar materials to the well-established silicon technology. µSPIRE pursues this goal through the development of a novel set of photon counting detectors integrated on a Si standard substrate. Single-photon detectors are crucial in several fields such as quantum information, medical physics, security, metrology, aerospace, electronics and biotechnology. In practical applications, solid-state devices, such as single-photon avalanche diodes (SPADs), offer unparalleled advantages, e.g. in terms of compactness, robustness, reliability and ease of operation, over photomultiplier tubes or superconductive detectors. Moreover, silicon SPADs can be micro-fabricated in arrays (called SiPM) in order to achieve photon-number resolving (PNR) capability that is essential for medical applications (like PET scanners), LIDAR, quantum computing, and others. SiPMs demonstrated so far are all silicon based (thus limiting their sensitivity to wavelengths shorter than 1.1 µm) and their planar fabrication technology sets a trade-off between fill factor (i.e. the ratio between photon-sensitive area and overall area) and number of micro-cells.
Our purpose is to go beyond the state-of-the-art, by employing a novel deposition approach, which we termed vertical heteroepitaxy (VHE). VHE exploits the patterning of conventional Si substrates, in combination with epitaxial deposition, to attain the self-assembly of arrays of epitaxial micro-crystals elongated in the vertical direction. VHE is particularly suited for the deposition of epitaxial heterostructures. Indeed, besides Si-only devices, we will develop Ge/Si and GaAs/Si heterostructures, with structural and electronic properties unparalleled by “conventional” epitaxial growth. Such VHE micro-crystals are the elementary microcells for novel single-photon detectors with performance far beyond those of current state-of-the-art SPADs.