Geiger-mode avalanche photodiodes, history, properties and problems

Geiger-mode avalanche photodiodes (G-APDs) have been developed during recent years and promise to be an alternative to photomultiplier tubes. They have many advantages like single photon response, high detection efficiency, high gain at low bias voltage and very good timing properties but some of their properties, the dark count rate for example, can be a problem. Several types of G-APDs are on the market and should be selected carefully for a given application.