Investigation and optimization of HfO₂ gate dielectric on N-polar GaN: Impact of surface treatments, deposition, and annealing conditions

UV-assisted capacitance–voltage (C–V) and current–voltage (I–V) measurements were performed on ∼20 nm HfO2/GaN metal–insulator–semiconductor capacitors. The effects of surface preparation, predeposition treatment, HfO2 deposition process, post-deposition annealing environment interface characteristics studied. Surface preparation by etching in diluted BHF piranha etch prior to atomic layer (ALD) suppressed the states compared baseline sample possibly due removal native oxide impurities. UV/ozone treatment reduced one order magnitude formation a thin Ga2O3 interlayer. In situ ALD pretreatment with tri-methyl-aluminum/N2 plasma was also found reduce significantly sample. addition, thermal improved dielectric constant breakdown voltage as less damage. lowest average trap density achieved 1.64 × 1012 cm−2/eV an 16 deposition.