The effect of ultraviolet (UV) irradiation on the minority carrier recombination lifetime was studied using a laser-microwave photoconductance (LM-PCD) method for wafers oxidized at 700, 900, and 1000 degrees C and for different oxidation times at these temperatures. For wafers oxidized at 1000 degrees C, the lifetime was found to decrease with UV irradiation. For wafers oxidized at 700 and 900 degrees C, the lifetimes could decrease or increase depending on the duration of oxidation and UV irradiation.