An <i>n</i>+-<i>n</i>-<i>p</i> germanium avalanche photodiode

Abstract

Low-noise germanium avalanche photodiodes of an n+-n-p structure have been investigated. Deep n+-n-p junctions have a lower noise than shallow n+-p junctions because holes have a higher ionization coefficient in germanium, and these n+-n-p diodes have a higher hole-to-electron collection efficiency. An excess noise factor F≈7 at the multiplication factor of 10 are obtained at a wavelength of 1.3 μm, whereas F≈10 for n+-p diodes. An internal quantum efficiency of 70–80% is obtained at 1.3 μm.