Effect of the Growth Temperature and Nitrogen Precursor on the Structural and Electrical Transport Properties of SmN Thin Films

We report on the structural and electrical properties of epitaxial SmN thin films grown by molecular beam epitaxy. The effect of the growth temperature and nitrogen precursor, either pure molecular N2 or NH3 was investigated. The structural quality of SmN was assessed by X-ray diffraction and the epitaxial growth character is observed over the entire range of growth temperatures, from 300°C to 800°C, with both nitrogen precursors. The highest quality films are produced at a growth temperature of about 430°C by using N2 as a nitrogen precursor. Hall Effect and resistivity measurements establish that SmN films are heavily n-type doped semiconductors, suggesting the presence of nitrogen vacancies, a recurring phenomenon in rare earth nitride compounds.