Radio-frequency photoconductance decay (RF-PCD) is a contactless method of measuring minority carrier lifetime in silicon. Low detection limits and speed of measurement makes this method ideally suited for in-situ determination of silicon wafer passivation and contamination processes. Comparative measurements of copper contamination of silicon surfaces using RF- PCD and TXRF yield a detection limit of about 109 Cu/cm2. The fast detection of changes in surface defects enables the time resolved observation of surface passivation breakdown due to the exposure of the wafer to controlled atmospheres. While nitrogen does not attack the surface passivation, oxygen exposure results in immediate native oxide growth.