Characterization of Si wafer Surfaces after Wet Chemical Treatment by the Microwave Reflectance Photconductivity Decay Method with Surface Electric Field

Voltage is applied between an external electrode and a Si wafer to control surface recombination, and carrier lifetime is measured by the microwave reflectance photconductivity decay (µ-PCD) method. The voltage dependence of the lifetime changes depending on the surface Fermi level and the surface state density. We apply this method to Si wafers with various chemical treatments, and qualitatively characterize the surface properies from the dependence of lifetime on applied voltage. The change in the surface properties with time after the treatment is also investigated.