Threshold Voltage Engineering of Enhancement-Mode AlGaN/GaN Metal-Oxide-Semiconductor High Electron Mobility Transistors with Different Doping Concentration of In Situ Cl− Doped Al2O3

This work used mist chemical vapor deposition to deposit an in-situ Cl— doped Al2O3 film. 0.05 vol%, 0.1 vol%, and 0.15 vol% HCl were added to the precursor solutions for Cl— doping. The recess and Cl— doped Al2O3 gate dielectrics were used to form enhancement-mode AlGaN/GaN metal-oxide-semiconductor high electron mobility transistors. The Cl— doping was confirmed by X-ray photoelectron spectroscopy and the negative charge concentration was extracted by capacitance-voltage method. It was found that the doping concentration affects the gate leakage performance and the carrier transportation mechanisms of the gate leakage were investigated. By using the Cl— doped Al2O3 as the gate dielectric layer, the device performance was improved, including more positive threshold voltage, higher output current at the same overdrive voltage, and over 600 V off-state breakdown voltage. In addition, the temperature-dependent threshold voltage characteristics were investigated to estimate the Cl— dopant runaway.