High Gain and High Sensitive Blue-Ultraviolet Avalanche Photodiodes (APDs) of ZnSSe n+-i-p Structure Molecular Beam Epitaxy (MBE) Grown on p-type GaAs Substrates

High gain and high sensitive blue-ultraviolet avalanche photodiodes (APDs) are developed using high quality ZnSSe n+-i-p hetero-structure grown on p-type GaAs substrates by molecular beam epitaxy (MBE). The short wavelength APDs have been realized by a new technique of interface superlattice buffers between p-GaAs and p-ZnSe hetero-interfaces, by which we have overcome large interface energy barriers (>1 eV: for hole-conduction) and unstable dark leakage currents. Utilizing a benefit of the n+-i-p structure on p-GaAs, the short wavelength APDs have been designed with an thin transparent n+ window layer ( 90) and high sensitivities of 5–3 A/W in blue-ultraviolet optical region under very low reverse bias condition of 33 V.