Platinum silicide (PtSi) on p-silicon Schottky-barrier focal plane arrays (FPAs) are strong candidates for infrared (IR) detection up to a wavelength of about 5 microns. However, an inherently low quantum efficiency (about 1 percent at 4 microns) makes it important to maximize the fill factor or the area of the array that is IR-sensitive. Current designs use an n- guard ring around the PtSi diodes to suppress edge leakage. This is effective, but the guard-ring overlap can significantly reduce the sensitive area of the diode. An aluminum plate that is already used as a photon reflector above the diode in current designs can be positively biased as a field place to create a surface depletion layer around the diode periphery. This produces leakage current suppression equivalent to the guard ring without giving up IR-sensitive diode area.