1.4-kV Breakdown Voltage for AlGaN/GaN High-Electron-Mobility Transistors on Silicon Substrate.

In this letter, we present the device characteristics of AlGaN/GaN heterostructures grown on 4-in Si using various buffer thicknesses (TBuf). The transmission electron microscopic image confirms a low dislocation density (\9.7 \times \10^7\ \cm^-2) for our epilayers grown using thick buffer layers. An increase in mobility and a decrease in sheet resistance of these samples were observed owing to improved crystal quality for GaN on thick buffer. Highelectron-mobility transistors (HEMTs) tested for three-terminal off breakdown voltage (\3TBV) show signs of breakdown voltage saturation for gate–drain length (Lgd) exceeding 15 \mu\m. However, an increase in TBuf causes a drastic increase in \3TBV, and a high \3TBV of 1.4 kV was observed with a specific on-resistance of 9.6 \m\Omega\cdot\cm^2. A figure of merit (FOM = BV^2/Ron) of \2.6 \times \10^8\ \V^2\cdot\Omega^-1\cdot\cm^-2 was observed for our devices, which is the highest for an AlGaN/GaN HEMT grown on Si. [ABSTRACT FROM AUTHOR]