Mid-Infrared InAs/GaSb Superlattice Planar Photodiodes Fabricated by Metal–Organic Chemical Vapor Deposition

Mid-wavelength infrared planar photodiodes were demonstrated, in which both the epitaxy growth of InAs/GaSb superlattices and the thermal diffusion of p-type dopant were performed in production-scale metal–organic chemical vapor deposition reactors. The formation of a planar homojunction was confirmed by secondary ion mass spectroscopy and its I–V characteristics. A cut-off wavelength around 5 μm was determined in 77 K optical characterization, and photo-current as high as 600 nA was collected from a reverse-biased planar diode of 640 μm diameter. These preliminary results were obtained despite the structural degradation revealed by x-ray diffraction, and we attribute the degradation to the concert of thermal annealing and high Zn concentration behind the diffusion front.