This proposal describes an approach to realize InAs/GaSb type II superlattice focal plane arrays through planar processing. A problem with conventional mesa diode processing approaches is that nonradiative surface recombination at the exposed pn junction is extremely rapid, leading to surface leakage currents that limit the mesa diode performance. By eliminating etched sidewalls through planar processing, we expect edge leakage current to be greatly reduced without compromising areal leakage currents. Planar processing using sealed ampoules or a pseudo-closed box approach requires strict control of the partial pressures is required to obtain reproducible diffusion profiles and to avoid surface damage in both of these approaches. An alternative approach which we propose to follow is the open-tube diffusion from doped spin-on films, which are commercially available for a variety of dopant species, including zinc. We believe diffusion of zinc from spin on SiOx presents a simpler, more manufacturable approach to planar processing focal plane arrays than the ampoule approach or the pseudo-closed box approach.
Keywords: Inas/Gasb Type Ii Superlattice, Detector, Photodiode, Focal Plane Array, Planar Processing
