Abstract : High-electron-mobility transistors (HEMTs) based on AlGaN/GaN heterostructures are being developed for high power electronic. The presence of a two-dimensional electron gas (2DEG) at the AlGaN/GaN interface enables reaching high electron mobility (>1500 cm$^2$.V-1.s-1). For safety and reliability reasons, normally-off HEMTs are requested and can be obtained by the full recess approach, based on the removal of the AlGaN layer underneath the gate. The dielectric (Al$_2$O$_3$) and metal gate are directly deposited on the etched GaN surface to create a metal-insulator-semiconductor (MIS) structure, giving rise to the so-called MIS-HEMTs.
The final devices properties strongly depend on the quality of the buried Al$_2$O$_3$/GaN interface. Advanced chemical characterization of this critical interface is thus mandatory. Laboratory HAXPES has recently appeared and its use is quickly rising for optimizing technological devices [3]. It is here a promising technique to investigate a more realistic Al$_2$O$_3$/GaN interface, e. g. with a thick Al$_2$O$_3$ layer. We have developed specific protocols to investigate the impact of Al$_2$O$_3$ thickness, precursors and post-deposition anneal on the GaN surface oxidation and stoichiometry.
Eugénie Martinez, Tarek Spelta, Pedro Fernandes Paes Pinto Rocha, Marc Veillerot, Bérangère Hyot, et al.. Laboratory HAXPES of GaN structures for power electronic. HAXPES 2022 - The 9th International Conference on Hard X-ray Photoelectron Spectroscopy, May 2022, Himeji, Japan. ⟨cea-03689191⟩