Interfacial atomic site characterization by photoelectron diffraction for 4H-AlN/4H-SiC( ) heterojunction

The interfacial atomic structure of an AlN thin film on a nonpolar 4H-SiC( <?CDATA 112̄0?> ) substrate grown by atomic Al and N plasma deposition was studied by photoelectron diffraction and spectroscopy. The epitaxial growth of the thin film was confirmed by the comparison of element-specific photoelectron intensity angular distributions (PIADs). Depth profiles were analyzed by angle-resolved constant-final-state-mode X-ray photoelectron spectroscopy (AR-XPS). No polar angular dependence was observed in Al 2p spectra, while an additional intermixing component was found in interface-sensitive N 1s spectra. The site-specific N 1s PIADs for the AlN film and an intermixing component were derived from two N 1s PIADs with different binding energies. We attributed the intermixing component to SiN interfacial layer sites. In order to prevent SiN growth at the interface, we deposited Al on the SiC( <?CDATA 112̄0?> ) substrate prior to the AlN growth. A significant reduction in the amount of intermixing components at the AlN/SiC interface was confirmed by AR-XPS.