Surface passivation of backside-illuminated indium antimonide focal plane array

A novel surface passivation tailored to a two-dimensional array of small-area, gate-controlled InSb photovoltaic diodes fabricated on etch-thinned bulk InSb wafers, with backside illumination, is presented. The surface passivation is based on a controlled surface treatment that reduces the native oxide and is followed by photon-assisted deposition of SiO_x. Thinned bulk n-type InSb with (111) orientation forms two distinctive types of interface on the In and Sb faces, respectively. The In face forms an accumulated interface with reduced surface recombination velocity. The Sb face forms a slightly accumulated interface, with a relatively small concentration of fast and slow surface states. The current-voltage and differential resistance-voltage characteristics of implanted p⁺-n photodiodes exhibit nearly flat behavior up to 1-V reverse bias with reduced leakage currents. The R_o×A product of small-geometry diodes is 5×10⁴ Ω-cm² at 77 K