Effect of Al₂O₃ thickness and oxidant precursors on the interface composition and contamination in Al₂O₃/GaN structures

In this paper, we investigate the Al 2 O 3 /GaN critical buried interface of the next generation of gallium nitride (GaN)‐based transistors using time‐of‐flight secondary ion mass spectrometry (ToF‐SIMS) and hard X‐ray photoelectron spectroscopy (HAXPES). Results highlight that gallium oxidation at this interface is enhanced when increasing the Al 2 O 3 thickness from 3 up to 20 nm. Gallium oxidation is reduced when using both O 3 and H 2 O as oxidant precursors, compared with only H 2 O during the growth of Al 2 O 3 . In addition, the O 3 /H 2 O‐based Al 2 O 3 favors a reduction of contaminants such as hydrogen and carbon but enhances the presence of halides (Cl − and F − ) at this Al 2 O 3 /GaN interface.