Accurate method for the determination of bulk minority-carrier lifetimes of mono- and multicrystalline silicon wafers

Abstract

An accurate method for the determination of the bulk minority-carrier recombination lifetime of crystalline silicon wafers of typical thickness (<0.5 mm) is presented. The method consists of two main steps: first, both wafer surfaces are passivated with silicon nitride films fabricated at low temperature (<400 °C) in a remote plasma-enhanced chemical vapor deposition system. Second, the effective minority-carrier lifetime of the wafer is measured by means of the contactless microwave-detected photoconductance decay technique. Due to the outstanding degree of surface passivation provided by remote-plasma silicon nitride films, the bulk minority-carrier lifetime can be very accurately determined from the measured effective minority-carrier lifetime. The method is suited for the bulk minority-carrier lifetime determination of p-type and n-type silicon wafers with doping concentrations in the 1014–1017 cm-3 range. We demonstrate the potential of the method for commercially available float-zone, Czochralski, and multicrystalline silicon wafers of standard thickness.