In this paper, a high voltage normally-off trenched-and-implanted vertical JFET (TI-VJFET) in 4H-SiC is investigated by way of two-dimensional numerical simulations. The structure is simple to fabricate and is expected to be able to achieve a high current density. Detailed designs are presented for 1.7kV to 14kV normally-off 4H-SiC VJFETs. A good agreement has been reached between computer modeling and experimental 1.7kV normally-off TI-VJFET in 4H-SiC. The fabricated 1.7kV device shows a V-B(2) /P-on,P-sp value of 827MW/cm(2) at room temperature, which represents a substantial performance improvement to the state-of-the-art.