研究目的
To investigate the carrier transport mechanism of Mg/Au ohmic contact for lightly doped β-Ga2O3, including the formation of ohmic contacts, temperature dependence of specific contact resistance, and determination of the dominant current transport theory and effective barrier height.
研究成果
Ohmic contact was successfully formed on β-Ga2O3 using Mg/Au stacks after annealing at 400 °C, with specific contact resistance decreasing with temperature. The current transport mechanism is dominated by thermionic emission theory, as indicated by qE00/kT < 0.5, and the effective barrier height is 0.1 eV. This provides insights for improving β-Ga2O3-based power devices, with future work suggested on heavily doped materials.
研究不足
The study is limited to lightly doped β-Ga2O3; heavily doped cases are not investigated. The annealing temperature and time are fixed, potentially not optimized for all conditions. The temperature range for measurements is limited to 300-375 K, which may not cover all operational scenarios. The use of specific metal stacks (Mg/Au) may not be generalizable to other materials.
1：Experimental Design and Method Selection:
The study aims to form ohmic contacts using Mg/Au stacks on lightly doped β-Ga2O3 and analyze the current transport mechanism. The thermionic emission theory is employed to model the data.
2：Sample Selection and Data Sources:
Sn lightly doped (01)-oriented β-Ga2O3 substrates with a carrier concentration of about
3：94 × 10^17 cm^-3 were used. Data were collected from current-voltage measurements at temperatures from 300 to 375 K. List of Experimental Equipment and Materials:
Equipment includes a Keithley 2611A semiconductor characterization system for I-V measurements, Hall Effect 5500 PC measurement system for carrier concentration, thermal evaporation system for metal deposition, and standard lithography tools. Materials include β-Ga2O3 substrates, Mg metal (
4：999%), Au metal, cleaning solvents (methanol, acetone, deionized water, Piranha solution, HF), and Ar gas for annealing. Experimental Procedures and Operational Workflow:
Substrates were cleaned, metal layers (820 nm Mg and 600 nm Au) were deposited by thermal evaporation, annealed at 400 °C for 2 min under Ar, and TLM patterns were fabricated. I-V characteristics were measured at varying temperatures, and specific contact resistance was extracted using TLM.
5：Data Analysis Methods:
Specific contact resistance was calculated from TLM data, and temperature dependence was analyzed by fitting to the thermionic emission model to determine the effective barrier height.
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