Areverse bias is applied to a pn junction, which acts as a capacitor. light strikes the surface, and holes and electrons are created which move towards the opposite charge.
accelerated electrons are emitted from a photosensitive surface and strike a second surface, knocking more than one electron from that surface and towards another surface. this process is repeated until there are more than electrons collected per photon that strikes the first surface.
a two‑dimensional array of pn junctions that stores electrons until they are read sequentially with a very high quantum efficiency.