JFET having width defined by trench isolation

A junction field-effect transistor (JFET) includes a substrate having a first-type semiconductor surface including a topside surface, and a top gate of a second-type formed in the semiconductor surface. A first-type drain and a first-type source are formed on opposing sides of the top gate. A first deep trench isolation region has an inner first trench wall and an outer first trench wall surrounding the top gate, the drain and the source, and extends vertically to a deep trench depth from the topside surface. A second-type sinker formed in semiconductor surface extends laterally outside the outer first trench wall. The sinker extends vertically from the topside surface to a second-type deep portion which is both below the deep trench depth and laterally inside the inner first trench wall to provide a bottom gate.