Voltage- and Temperature-Dependent Degradation of AIN/GaN High Electron Mobility Transistors

We investigated the voltage- and temperature -dependent degradation of AIN/GaN high electron mobility transistors with gate lengths of 70 nm and 100 nm. The devices under test were dc stressed in semi-on-state conditions at constant power dissipation of $4.5\displaystyle \frac {\mathrm {w}}{\mathrm {m}\mathrm {n}}$ for approximately 200h or until the drain saturation current $I_{\mathrm {D}\mathrm {S}\mathrm {S}}$ dropped by 10 %. To examine whether a Arrhenius like temperature acceleration and additionally voltage acceleration can be ascertained, the channel temperature and stress voltage were varied. In our tests, both acceleration factors could be confirmed and are shown to be interdependent. Arrhenius fits resulted in activation energies between 0.80 eV and 1.12 eV. A generalized Eyring approach is used to model the combined acceleration by temperature and voltage as well as their interdependency.