Silicon carbide (SiC) n-channel and p-channel junction field-effect transistors (JFETs) were fabricated by direct ion implantation into a high-purity semi-insulating 4H-SiC substrate toward complementary-JFET integrated circuit applications under a harsh environment. The fabricated n-JFET and p-JFET on a common substrate without an epitaxial layer show normal transistor operations up to 400 °C. Their electrical characteristics are comparable with theoretical estimations obtained from material parameters of n- and p-type SiC epitaxial layers. The present results assure that not only JFETs but also a variety of devices can be made by direct ion implantation while keeping material properties of epitaxially grown SiC.