a silicon on insulator field effect transistor structure is formed on a conventional bulk silicon wafer . the structure includes an electrical coupling between the channel region of the fet with the bulk silicon substrate to eliminate the floating body effect caused by charge accumulation in the channel regions due to historical operation of the fet . the method of forming the structure includes isolating the fet active region from other structures in the silicon substrate by forming an insulating trench about the perimeter of the fet and forming an undercut beneath the active region to reduce or eliminate junction capacitance between the source and drain regions and the silicon substrate .