A field effect transistor of SiC for high temperature application has the source region layer (4), the drain region layer (5) and the channel region layer (6, 7) vertically separated from a front surface (14), where a gate electrode (12) is arranged, for reducing the electric field at said surface in operation of the transistor and in the case of operation as a gas sensor permitting all electrodes except for the gate electrode to be protected from the atmosphere.