A silicon on insulator substrate includes a semiconductor bulk handle wafer, an insulating layer on said semiconductor bulk handle wafer and a semiconductor film on said insulating layer. An opening extends completely through the semiconductor film and insulating layer to expose a surface of the semiconductor bulk handle wafer. Epitaxial material fills the opening and extends on said semiconductor film, with the epitaxial material and semiconductor film forming a thick semiconductor film. A trench isolation surrounds a region of the thick semiconductor film to define an electrical contact made to the semiconductor bulk handle wafer through the opening.