extends out from underneath the source region 142 into the cavity 160 directly below the transistor gate structure 140 when the sige removal step 110 is complete the cantilever arm 164 can flex freely within the cavity 160 toward or away from the transistor gate structure 140 based on an electric potential of the gate electrode 150 relative to an electric potential of the cantilever arm 164 in operation when a sufficient positive voltage exceeding a threshold value is applied to the gate electrode 150 the doped cantilever arm 164 is deflected toward the oppositely doped gate the cantilever arm 164 may flex enough that the tip 166 makes physical and electrical contact with the base of the drain region 144 when such contact occurs the electromechanical switch is closed as a current path is established from the source region 142 to the drain region 144 wherein the cantilever arm 164 serves as a transistor channel the threshold voltage can be tuned during fabrication by adjusting the thickness of the additional silicon layer 128 in addition a voltage e g in the range of about 3 4 v can be applied via a backside electrical contact to the silicon substrate 114 to back bias the box layer 116 so as to repel the cantilever arm 164 and assist in moving the tip 166 toward the drain region 144 the box layer 116 thus may serve as a back gate when the voltage applied to the gate electrode 150 no.