InAlAs Avalanche Photodiode With Type-II Superlattice Absorber for Detection Beyond 2 μm

An avalanche photodiode (APD) using a InAlAs mul- tiplication region and a type-II InGaAs/GaAsSb superlattice as the absorber (both lattice matched to InP) is reported. An optical and electrical characterization of the photodiode is performed. The APD exhibited an absorption cutoff wavelength of 2.5 μm, which is expected from the InGaAs/GaAsSb superlattice. A responsivity of 0.47 A/W (without gain) for the APD at a 2004-nm wavelength was demonstrated. The APD breakdown voltage showed a weak temperature dependence of ∼40 mV/K, as a result of the excellent temperature stability in InAlAs. Index Terms—Avalanche photodiode (APD), infrared, quantum well (QW), superlattice, type II.