Low interface trap density in AlGaN/GaN Metal-Insulator-Semiconductor High-Electron-Mobility Transistors on CVD-Diamond

The interface trap behavior in SiNx/AlGaN/GaN metal-insulator-semiconductor high-electron-mobility transistors (MIS-HEMTs) and Schottky HEMTs on CVD diamond was studied using parallel conductance techniques. In MISHEMTs, two different types of traps were identified, fast with the time constant $\tau_{\mathbf{T}}\equiv(\mathbf{0.1}-\mathbf{3.6})\mu\mathbf{s}$ and slow with $\tau_{\mathbf{T}}\equiv\mathbf{6}$ ms whereas, only fast traps were obtained in conventional HEMTs. These fast traps could be related to AlGaN/GaN hetero-interface which are identical in both the devices. The density of fast trap $(\pmb{D}_{\mathbf{TT}})$ is almost similar for MIS-HEMTs and HEMTs (∼of $\mathbf{0.7}-\mathbf{8\ x\ 10}^{\mathbf{11}}\mathbf{cm}^{-\mathbf{2}}\mathbf{eV}^{-\mathbf{1}})$ . The density of slow trap $(\pmb{D}_{\mathbf{Ts}})$ in MIS-HEMTs was estimated as $\sim\mathbf{6}-\mathbf{11\ x\ 10}^{\mathbf{12}}\mathbf{cm}^{-\mathbf{2}}\mathbf{eV}^{-\mathbf{1}}$ which could be related to the Schottky/dielectric interface.