Dielectric Thickness and Fin Width Dependent OFF-State Degradation in AlGaN/GaN SLCFETs

Accelerated OFF -State stressing of multichannel AlGaN/GaN Superlattice Castellated Field Effect Transistors (SLCFET) with varying dielectric thickness $(d_{i})$ and fin-width $(W_{fi n})$ was studied using noise measurements. As $d_{i}$ increased, the failure mechanism changed from an abrupt breakdown to gradual time dependent dielectric breakdown (TDDB). Smaller $W_{fi n}$ is found to extend lifetime compared to wider $W_{fi n}$ under such stressing condition. Percolation theory and associated trap generation during stressing can explain the observed behavior.