Monocrystalline semiconductor photodetector

Abstract

A semiconductor photodetector having a planar structure, including a first silicon layer having a first conductivity and formed with a recess, a silicon dioxide film covering a sidewall of the recess therewith, a germanium monocrystal layer formed in the recess, a first germanium layer having a first conductivity and sandwiched between the germanium monocrystal layer and the first silicon layer in the recess, a second germanium layer having a second conductivity and formed on the germanium monocrystal layer, and a second silicon layer having a second conductivity and formed on the second germanium layer. The first and second germanium layers prevent a depletion layer, which are generated in the germanium monocrystal layer when a voltage is applied to the semiconductor photodetector, from reaching the first and second silicon layers, respectively. In accordance with the semiconductor photodetector, a depletion layer generated in the germanium monocrystal layer is prevented from reaching the first and second silicon layers, and hence, electric charges generated by introduction of light into the germanium monocrystal layer would not be recombined to each other through a recombination core. As a result, it is possible to avoid reduction in a photoelectric current or a quantum efficiency.