A method for measuring denuded zone depth from lifetime measurements is proposed and compared to observations by microscopy techniques. The surface photovoltage (SPV) method is chosen for measuring lifetime, as it is found to be extremely sensitive to oxygen precipitation. SPV estimates of denuded zone depth are compared to observations by microscopy techniques, such as selective etching and inspections by a scanning electron microscope or an atomic force microscope, and analysis by transmission electron microscopy. SPV estimates agree with microscopy inspection, provided defect density is high enough to allow a denuded zone to be identified.