研究目的
To fabricate a diamond metal–semiconductor field-effect transistor (MESFET) with a Pt Schottky gate that exhibits high breakdown voltage and operates at high temperatures.
研究成果
Diamond MESFETs with a Corbino geometry were fabricated, exhibiting normally-on behavior with clear pinched-off characteristics at both room temperature and 300 °C. The breakdown voltage reached 1530 V at a gate-drain length of 30 μm, the highest reported for a diamond FET to date.
研究不足
The breakdown voltage is degraded more than 30% after breakdown characterization due to critical damage on the devices. The estimated electrical field at breakdown is lower than the ideal value for diamond, possibly due to field spikes at the drain edge of the gate electrode.
1：Experimental Design and Method Selection:
The MESFET was fabricated using a lightly doped p-type channel and a wide gate-drain length device structure to achieve high breakdown voltages. A Corbino (circular) type structure was utilized for device fabrication without requiring device isolation.
2：Sample Selection and Data Sources:
A high-pressure and high-temperature synthetic Ib (001) semi-insulating single-crystal diamond substrate was used. The p-type layer was deposited using microwave plasma assisted chemical vapor deposition (MWCVD).
3：List of Experimental Equipment and Materials:
Equipment included a parameter analyzer (Agilent 4156C), a vacuum probe system (Nagase Techno-Engineering), a power device analyzer (Agilent, B1505A), and a probe system (Vector Semiconductor). Materials included Ti/Au for ohmic contacts and Pt/Au multilayers for the Schottky gate.
4：Experimental Procedures and Operational Workflow:
The p-type layer was deposited, followed by the fabrication of Ti/Au ohmic contacts and Pt/Au Schottky gates using photolithography and lift-off techniques. The surface was exposed to UV light under an ozone atmosphere for stable oxygen surface termination.
5：Data Analysis Methods:
Current-voltage (I-V) characteristics were measured, and breakdown measurements were conducted at room temperature in an insulating liquid to prevent surface discharge.
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