Why ohmic contacts are required in JFET?
If you have metal contacting a lightly doped semiconductor material, it tends to behave as a diode. In fact, this is how Schottky diodes are made. So, to get the desired transistor characteristic, the metal contacts need to contact silicon that is highly doped with the same polarity as the semiconductor material or channel polarity. So you would have N+ ohmic contacts for N channel fet, and P+ ohmic contacts for P channel JFET. Even if it weren't for the Schottky effect, you would still want ohmic contacts to minimize the contact resistance, to get the full effect of the JFET.
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