Effect of surface passivation on generation and recombination lifetimes in silicon wafer studied by impedance spectroscopy

Abstract

Impedance spectroscopy is used to study the effect of surface passivation on minority carrier lifetimes. The technique allows measurement of generation and recombination lifetimes separately. Induced p+-p-n structures are prepared by depositing semitransparent layers of high and low work function metals (Pd and Al, respectively) on the two sides of silicon wafers. Hydrogen adsorption property of Pd surface has been utilized for passivation. The generation lifetimes remain almost unaffected but recombination lifetimes enhance many folds after passivations which are in agreement with values obtained by microwave photoconductive decay technique after chemical passivation. Variations are analyzed for estimation of bulk recombination lifetime.