Electrical and optical performances of InGaAs/GaAsSb superlattice short-wavelength infrared detectors

Abstract

We report on a p-i-n photodetector based on type II InGaAs/GaAsSb SLs with a cutoff wavelength of 2.5 μm at room temperature. High quality materials were grown on an n-type (100) InP substrate by molecular beam epitaxy. Photoluminescence spectroscopy peak of the SLs around 2.5 μm and atomic steps in the atomic force microscope image were clearly observed. A device with the 100% cutoff wavelength of 2.5 μm at 293 K was fabricated. Temperature-dependent current-voltage measurements show that the diffusion current and generation-recombination current dominate at temperatures higher than 200 K while the generation-recombination current and trap-assisted tunneling current dominate at temperatures below 200 K. The optical response measurement quantum efficiency increases with reverse bias, and a diffusion length of 0.3 μm was extracted. The cause of the small diffusion length and possible approaches to improve it were briefly discussed.