In this article scanning capacitance measurements (SCM), carried out directly on device sections, are presented. Quantitative SCM have been applied to determine the channel length in an advanced power metal-oxide-semiconductor device and the base width in a heterojunction bipolar transistor. Ion implantation in samples with 45 degrees-edge mask allowed us to demonstrate the SCM capability to image the depletion region and to delineate the junction position. The effective channel length was determined by considering the depletion region. A channel length of less than 200 nm was determined. Measurements on a heterojunction bipolar transistor device allowed us to image a base width of less than 180 nm.