Minority-carrier lifetime analysis of silicon epitaxy and bulk crystals with nonuniformly distributed defects

Existing analyses of the pulsed response of an MOS capacitor for minority-carrier lifetime determination result in a lifetime value averaged over most of the depletion region width. The authors present an analysis of MOS capacitance-versus-time data that enables minority-carrier generation lifetime to be plotted as function of depletion-region depth. The technique is shown to be useful for samples with bulk or buried interfacial layer defects that have defect-free surfaces. Data are presented for intrinsically gettered bulk crystals and extrinsically gettered Si (2%Ge) epitaxial layers with misfit dislocations. For samples that do have uniform lifetimes, the measurement time required for determining carrier lifetime is reduced by more than an order of magnitude