Metallic β-Nb2N Films Epitaxially Grown by MBE on Hexagonal SiC Substrates

RF-plasma MBE was used to epitaxially grow 4 - 100-nm-thick metallic β-Nb2N thin films on hexagonal SiC substrates. When the N/Nb flux ratios are greater than one, the most critical parameter for high-quality β-Nb2N is the substrate temperature. The X-ray diffraction (XRD) of films grown between 775 °C and 850 °C demonstrates pure β-Nb2N phase formation which was also confirmed by X-ray photoelectron spectroscopy and transmission electron microscopy measurements. Using the (0002) and (2131) XRD peaks of a β-Nb2N film grown at 850 °C reveals a 0.68% lattice mismatch to the 6H-SiC substrate. This suggests that β-Nb2N can be used for high-quality metal/semiconductor heterostructures that cannot be fabricated at present.