Design and passivation of short-/mid-wavelength dual-color infrared detector photodiodes based on InAs/GaSb type II superlattice

A kind of short-/mid-wavelength dual-color type-II InAs/GaSb superlattice infrared detector photodiode with low dark current density and high RA value at 77 K is presented. The 320 x 256 focal plane arrays photodiodes which followed a p-i-n-n-i-p structure design are realized by two back-to-back p-i-n junctions, the band energy diagram was numerically simulated and analyzed detailly. To solve the passivation problem of dual-color photodiode with deeper mesa and steeper sidewall, two methods of surface passivation were performed, (NH4)(2)S and anodic sulfide respectively. Compared to un-passivated device, the RA value of the passivated device is improved by three orders of magnitude for MWIR and at least one order of magnitude for SWIR, the better RA value was achieved by introducing the anodic sulfide and SiO2 passivation technology. The work shows a better suppression of the surface leakage current, with a resistivity of the surface and sidewalls superior to 3.6 x 10(7) omega center dot cm for MWIR and 5.2 x 10(8) omega center dot cm for SWIR. At last, the work shows good thermal image results.