270 results about "Single-photon avalanche diode" patented technology

A single-photon avalanche diode (SPAD) is a solid-state photodetector in which a photon-generated carrier (via the internal photoelectric effect) can trigger a short-duration but relatively large avalanche current. This avalanche is created through a mechanism called impact ionization, whereby carriers (electrons and/or holes) are accelerated to high kinetic energies through a large potential gradient (voltage). If the kinetic energy of a carrier is sufficient (as a function of the ionization energy of the bulk material) further carriers are liberated from the atomic lattice. The number of carriers thus increases exponentially from, in some cases, as few as a single carrier. This mechanism was observed and modeled by John Townsend for trace-gas vacuum tubes, becoming known as a Townsend discharge, and later being attributed to solid-state breakdown by K. McAfee. This device is able to detect low-intensity ionizing radiation, including: gamma, X-ray, beta, and alpha-particle radiation along with electromagnetic signals in the UV, Visible and IR (in the optical case this can be down to the single photon level). SPADs are also able to distinguish the arrival times of events (photons) with a timing jitter of a few tens of picoseconds.