ENHANCEMENT DEPLETION MESFETS OF DIAMOND AND THEIR LOGIC-CIRCUITS/

Using the p-type surface-conductive layer of diamond film, enhancement mode and depletion mode MESFETs have been fabricated by changing the metals of the gate electrode. The threshold voltages of MESFETs depend on the electronegativity of the metals. A MESFET with a Cr gate was o perated in depletion mode and exhibited a peak transconductance of 12. 3 mS mm(-1), which is the highest in diamond FETs. This high performan ce can be obtained by a self-aligned gate fabrication process, which m inimizes the spacing between the ohmic contacts and the Schottky conta ct. By utilizing an E-MESFET for the driver and a D-MESFET for the act ive load, E/D-type logic circuits such as NOT, NAND and NOR circuits h ave been fabricated for the first time. (C) 1997 Elsevier Science S.A.