NOVELTY - The method comprises exposing a lead salt-coated substrate to at least one of oxygen and nitrogen for 1-60 minutes, preferably 15-25 minutes at a temperature of 300-450 degrees C, preferably 435-445 degrees C, followed by a step of exposing the lead salt-coated substrate to an iodine atmosphere for 1-60 minutes, preferably 5-20 minutes at a temperature of 300-450 degrees C, preferably 370-385 degrees C to form a sensitized lead salt-coated substrate. The method further comprises coating a portion of the sensitized lead salt-coated substrate with a metal to form a detector.    USE - The method is useful for sensitizing a lead salt film that is useful in a substrate of a photodetector such as a photoconductive detector and a photovoltaic detector of a laser, a solar cell and an image sensor (all claimed).    ADVANTAGE - The method is capable of reliably improving the detectivity of chemically deposited lead salt films and decreasing the manufacturing cost and improving the uniformity of polycrystalline lead salt photoconductive and photovoltaic photodetectors.    DETAILED DESCRIPTION - The method comprises exposing a lead salt-coated substrate to at least one of oxygen and nitrogen for 1-60 minutes, preferably 15-25 minutes at a temperature of 300-450 degrees C, preferably 435-445 degrees C, followed by a step of exposing the lead salt-coated substrate to an iodine atmosphere for 1-60 minutes, preferably 5-20 minutes at a temperature of 300-450 degrees C, preferably 370-385 degrees C to form a sensitized lead salt-coated substrate. The method further comprises coating a portion of the sensitized lead salt-coated substrate with a metal to form a detector, which has a detectivity of 2x 109 to 2x 1011 cm.Hz(1/2).W-1, 1x 1010 to 2x 1011 cm.Hz(1/2).W-1, 2x 1010 to 2x 1011 cm.Hz(1/2).W-1, 2.5x 1010 to 2x 1011 cm.Hz(1/2).W-1 or 2.8x 1010 to 2x 1011 cm.Hz(1/2).W-1 when uncooled. An INDEPENDENT CLAIM is included for a photodetector.    DESCRIPTION OF DRAWING(S) - The figure shows a schematic cross-sectional view of a detector.    Sample I (a)    Sample II (b)    Sample III. (c)