High-Quality Interface in ${\rm Al}_{2}{\rm O}_{3}/{\rm GaN}/{\rm GaN}/{\rm AlGaN}/{\rm GaN}$ MIS Structures With In Situ Pre-Gate Plasma Nitridation

We report an in situ low-damage pre-gate treatment technology in an atomic layer deposition (ALD) system prior to the ALD- Al₂O₃ deposition, to realize high-quality Al₂O₃/III-nitride (III-N) interface. The technology effectively removes the poor quality native oxide on the III-N surface while forming an ultrathin monocrystal-like nitridation interlayer (NIL) between Al₂O₃ and III-N surface. With the pre-gate treatment technology, high-performance Al₂O₃(NIL)/GaN/AlGaN/GaN metal-insulator-semiconductor high-electron-mobility transistors are demonstrated, exhibiting well-behaved electrical characteristics including suppressed gate leakage current, a small subthreshold slope of ~64 mV/dec, and a small hysteresis of ~0.09 V.