A novel method for the simultaneous characterization of bulk impurities and surface states by photocurrent measurements

A nsw method for evaluating both surface recombination velocity and bulk mi nority carrier lifetime by photocurrent measurements was proposed and valid ated by comparison with capacitance-voltage measurements of interface state density. This method is an evolution of the measurement of surface recombi nation velocity by the Elymat technique. It does nor require the oxide to b e etched off and consists of measurements of surface recombination velocity under an applied surface bias. The application of a surface bias allows th e control of the interface potential and the identification of the suitable interface condition such that surface recombination velocity can be consid ered as a measurement of interface state density. In addition, it is shown that surface recombination velocity is suppressed when the surface is under accumulation conditions, so the application of a surface bias provides the possibility of a surface passivation by driving the surface into accumulat ion. This passivation by surface polarization is about as effective as the chemical passivation by HE Finally, the dependence of surface recombination velocity on the injection level is shown to be reversed when the interface changes from depletion to accumulation or inversion conditions. (C) 2000 T he Electrochemical Society. S0013-4651(99)09-08 1-3. All rights reserved.