Si+ and Si- emissions from n and p type Si wafers (uniformly doped) during the initial stages of sputtering with Cs+ ions (transient region) scale with work functions in an expontential fashion consistent with the electron tunneling model. Work functions were derived using the Kelvin probe method. The intensity-work function dependence is also shifted according to the initial work functions of these wafers. As a result, almost identical transient effects are exhibited, i.e. matrix ion intensities do not appear to scale with dopant concentrations. This implies that intensity-work function relations are substrate dependent. Cs+ intensities were also studied. (C) 2004 Elsevier B.V. All rights reserved.