Role of Gate Hole Injection in Minimizing Substrate Coupling and Electron Trapping in AlGaN/GaN Power HEMTs

We investigate the role of gate hole injection in reducing the charge trapping phenomena in AlGaN/GaN power HEMTs submitted to semi-on stress at grounded, negative, and positive substrate bias. We demonstrate that (even during short measuring pulses) holes injected from the gate are easily retained by ionized carbon acceptors within the SCR (Space Charge Region) region in UID/C:GaN (Unintentionally Doped/ Carbon Doped) when a negative substrate is applied, suppressing the capacitive coupling between substrate and 2DEG that is responsible for the channel depletion. The role of substrate bias in modifying the internal field distribution and the related trapping processes is discussed in detail.