AlGan/Gan metal-oxide-semiconductor high electron mobility transistors (MOS-HEMTs) with novel gate oxides

Abstract

AlGaN/GaN metal-oxide-semiconductor high electron mobility transistors (MOS-HEMTs) with reactive-sputtered high dielectric constant (high-k) HfO2 and pulsed-laser-deposition (PLD) grown epitaxial Sc2O3 gate oxides were successfully fabricated and characterized in this work. Owing to the good oxide quality and excellent interface characteristics of these oxide/HEMT heterostructures, both HfO2- and Sc2O3-based MOS-HEMTs exhibited significant enhanced device performance relative to the regular Schottky-gate HEMTs. These include higher driving current capacity, lower gate leakage current, larger gate voltage swing, faster small-signal response, and a better immunity to drain current collapse. When comparing between these two kinds of MOS-HEMTs, HfO2 MOS-HEMTs have the advantages in terms of efficient gate modulation, such as a larger device transconductance due to the high-k property of HfO2, while the Sc2O3 counterpart prevailed in maximum drain current density, gate leakage and the pulsed-mode characteristics, most probably a direct consequence of the epitaxial nature of the PLD-grown Sc2O3 gate oxide.