研究目的
Investigating the in-situ oxidation of Ir, Pd, Pt, Ag, and Au Schottky contacts on (010) β-Ga2O3 to produce high-quality SCs with large barriers and thermal stability for high-temperature unipolar devices.
研究成果
In-situ oxidation during Schottky contact fabrication on (010) β-Ga2O3 significantly increases barrier heights for various metals, with oxidized SCs showing barriers pinned around 2.2-2.4 eV due to possible metal-induced gap states, compared to 1.3-1.5 eV for plain metals due to oxygen vacancies. This results in excellent high-temperature performance with high rectification, indicating potential for high-temperature device applications.
研究不足
The study is limited to specific metals (Ir, Pd, Pt, Ag, Au) and the (010) face of β-Ga2O3. The oxidized layers may not form high-quality semiconductor heterojunctions due to room temperature deposition. Thermal stability of AuOx is questionable above 120°C. The mechanisms of Fermi level pinning are attributed but not definitively proven.
1：Experimental Design and Method Selection:
The experiment involved fabricating Schottky contacts on (010) β-Ga2O3 substrates using reactive rf sputtering with O2:Ar plasma for oxidized metals and inert Ar plasma for plain metals. The design aimed to compare barrier heights and ideality factors between plain and oxidized metal SCs.
2：Sample Selection and Data Sources:
Unintentionally-doped bulk single-crystal (010) β-Ga2O3 substrates from Tamura Corp. Japan were used. Samples were diced into 5.0 mm × 5.0 mm × 0.5 mm pieces. Electrical properties (resistivity, carrier density, mobility) were measured using Hall Effect measurements.
3：0 mm × 0 mm × 5 mm pieces. Electrical properties (resistivity, carrier density, mobility) were measured using Hall Effect measurements.
List of Experimental Equipment and Materials:
3. List of Experimental Equipment and Materials: Equipment includes rf sputtering system, HP4155A parameter analyzer, e-beam evaporator, photolithography setup. Materials include Ir, Pd, Pt, Ag, Au targets (99.95% purity), Ti/Au for ohmic contacts, organic solvents for cleaning.
4：95% purity), Ti/Au for ohmic contacts, organic solvents for cleaning.
Experimental Procedures and Operational Workflow:
4. Experimental Procedures and Operational Workflow: Samples were cleaned ultrasonically in organic solvents. SCs were deposited at room temperature using rf sputtering with Ar or O2:Ar plasma. Circular SCs (area 1.34×10-3 cm-2) were fabricated via lift-off photolithography. Oxidized SCs were capped with plain metal. Ti/Au ohmic contacts were deposited by e-beam evaporation. I-V characteristics were measured using an HP4155A parameter analyzer in the dark.
5：34×10-3 cm-2) were fabricated via lift-off photolithography. Oxidized SCs were capped with plain metal. Ti/Au ohmic contacts were deposited by e-beam evaporation. I-V characteristics were measured using an HP4155A parameter analyzer in the dark.
Data Analysis Methods:
5. Data Analysis Methods: I-V characteristics were fitted using thermionic emission theory to extract barrier height and ideality factor. Image-force lowering corrections were applied. Data was analyzed for correlation with metal work function and compared to Schottky-Mott model.
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