The authors fabricate and characterize dual-gated graphene field-effect transistors (FETs) using Al₂O₃ as the top-gate dielectric. They employ a thin Al film as a nucleation layer to enable atomic layer deposition (ALD) of Al₂O₃. The devices exhibit carrier mobilities of over 8,000 cm²/Vs at room temperature, indicating that the top-gate stack does not significantly degrade device performance. The study introduces a device model that fits the experimental data using a single mobility value. The key innovation is the use of a thin Al layer as a nucleation site for ALD Al₂O₃, which allows for uniform and high-quality dielectric deposition on graphene. The transport characteristics of the devices are measured, showing minimal leakage current and a high dielectric quality. The extracted mobility value is consistent with theoretical predictions, suggesting that the mobility is primarily determined by fixed impurity scattering. These results are promising for high-speed FETs and novel graphene-based device designs.The authors fabricate and characterize dual-gated graphene field-effect transistors (FETs) using Al₂O₃ as the top-gate dielectric. They employ a thin Al film as a nucleation layer to enable atomic layer deposition (ALD) of Al₂O₃. The devices exhibit carrier mobilities of over 8,000 cm²/Vs at room temperature, indicating that the top-gate stack does not significantly degrade device performance. The study introduces a device model that fits the experimental data using a single mobility value. The key innovation is the use of a thin Al layer as a nucleation site for ALD Al₂O₃, which allows for uniform and high-quality dielectric deposition on graphene. The transport characteristics of the devices are measured, showing minimal leakage current and a high dielectric quality. The extracted mobility value is consistent with theoretical predictions, suggesting that the mobility is primarily determined by fixed impurity scattering. These results are promising for high-speed FETs and novel graphene-based device designs.