Atomic Layer Epitaxy AlN for Enhanced AlGaN/GaN HEMT Passivation

Enhancements in AlGaN/GaN high-electron-mobility transistor (HEMT) performance have been realized through ultrathin (4 nm) AlN passivation layers, formed by atomic layer epitaxy (ALE). A combination of ex situ and in situ surface cleans prepare the surface for deposition of ALE AlN. HEMTs passivated by high crystallinity AlN, grown at 500
$^{\circ}{\rm C}$
, show improvements in 2-D electron gas sheet carrier density, gate leakage current, off-state drain leakage current, subthreshold slope, and breakdown voltage. In addition, degradation of dynamic on resistance during pulsed off-state voltage switching stress is suppressed by
${\sim}{50\%}$
compared with HEMTs passivated by conventional plasma enhanced chemical vapor deposition
${\rm SiN}_{x}$
.