Impact Ionization in InAs Electron Avalanche Photodiodes

A systematic study of impact ionization, avalanche multiplication, and excess noise in InAs diodes has been carried out, confirming that avalanche multiplication is dominated by the impact ionization of electrons. This results in highly desirable “electron avalanche photodiode” characteristics previously only demonstrated in HgCdTe diodes, which are discussed in detail. The suppression of excess noise by nonlocal effects, to levels below the local model minimum of F = 2, is explained. An electron ionization coefficient is calculated and shown to be capable of modeling the electron impact ionization, which differs characteristically from that in wider bandgap III-V materials.