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, based on a controlled surface treatment that reduces the native oxide and subsequently followed by photon-assisted deposition of SiO(x), is reported. Thinned bulk n-type indium antimonide (InSb) with (111) orientation forms distinctively two types of interfaces on the indium and antimony faces, respectively. The indium face forms an accumulated interface with reduced surface recombination velocity. The antimony face, where the junctions are implanted, forms a slightly accumulated interface, with a relatively small concentration of fast and slow surface states, as exhibited by near ideal capacitance-voltage characteristics of MIS devices and very small hysteresis (0.15 V for a 10 V span, measured at 77 K). 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 R0 . A product of small-geometry diodes with junction area of 9 x 10(-6) cm2 is 5 X 10(4) OMEGA - cm2 at 77 K. These results characterize the performance after the complete processing steps that are required for the fabrication of backside-illuminated focal plane array on a thinned bulk wafer processed on both sides.