Semiconductor devices, such as a lateral HEMT, may display current flow between a plurality of interdigitated source fingers and drain fingers, and controlled by a common gate connection. An extended source finger contact may enable improved voltage control across the source fingers, even for large devices with many and/or lengthy source fingers. In this way, unwanted subthreshold operations and switching oscillations may be avoided by reliably maintaining a source voltage at a desired level, to thereby provide fast and reliable switching.