A junction field effect transistor (JFET) has a hyperabrupt junction layer that functions as a channel of a JFET. The hyperabrupt junction layer is formed by two dopant profiles of opposite types such that one dopant concentration profile has a peak concentration depth at a tail end of the other dopant profile. The voltage bias to the channel is provided by a body that is doped with the same type of dopants as the gate. This is in contrast with conventional JFETs that have a body that is doped with the opposite conductivity type as the gate. The body may be electrically decoupled from the substrate by another reverse bias junction formed either between the body and the substrate or between a buried conductor layer beneath the body and the substrate. The capability to form a thin hyperabrupt junction layer allows formation of a JFET in a semiconductor-on-insulator substrate.