Junction field-effect transistors with vertical channels and self-aligned regrown gates and methods of making these devices are described. The methods use techniques to selectively grow and/or selectively remove semiconductor material to form a p-n junction gate along the sides of the channel and on the bottom of trenches separating source fingers. Methods of making bipolar junction transistors with self-aligned regrown base contact regions and methods of making these devices are also described. The semiconductor devices can be made in silicon carbide.