Effect of interfacial reactions between atomic-layer-deposited HfO2 films and n-GaAs (100) substrate using postnitridation with NH3 vapor

Abstract

Using a variety of various physical measurements, the effects of postnitridation annealing using NH3 vapor on the interface between atomic-layer-deposited HfO2 films and n-GaAs (100) substrates were investigated. After the nitridation treatment, from x-ray absorption spectroscopy and high resolution x-ray photoemission spectroscopy data indicate that the incorporation of Ga oxides into HfO2 films was significantly suppressed during the annealing treatment, primarily because of chemical reactions at the interface between Ga2O3 and NH3. Microstructural analyses further confirmed that the HfO2 film was fully crystallized and a thin GaOxNy layer had been formed at the HfO2/GaAs interface during the annealing process. Compared with the energy band alignments before and after the annealing process, the valence band offsets and energy band gaps were not changed substantially, because the interfacial nitride layer effectively blocked the diffusion of Ga oxide into the film.