A multi-function semiconductor device is provided. The device includes a bipolar transistor and an FET formed in parallel. A semiconductor substrate is provided on an insulating layer. A source/emitter region and a drain region are formed in the semiconductor substrate and border first opposite sides of a body region therebetween. A gate is formed above the substrate between the source/emitter region and the drain region to form an FET having three terminals including the gate, the source/emitter region, and the drain region. A collector region is formed in the substrate abutting the drain region and extending further under the gate and the drain region. A bipolar transistor having three terminals is formed including a base region, the source/emitter, and the collector region. A shortest distance between the collector region and the source/emitter region defines a base width.