Epitaxial Growth of ScAlN on (111) Si Via Molecular Beam Epitaxy
摘要
We report on the growth of epitaxial ScxAl1−xN (x = 0.3–0.4) on (111) Si substrates via molecular beam epitaxy. Growth of an AlN nucleation layer (NL) is sensitive to the III/V flux ratio, with more N-rich growth conditions leading to evidence of grain tilt and a degradation in the structural quality of subsequently grown ScAlN. Utilizing the optimized AlN NL III/V of 0.9, ScxAl1−xN films were grown with x = 0.3–0.4 having an x-ray diffraction 0002 reflection rocking curve full width at half maximum (FWHM) of 0.69°–1.14°. Incorporation of a graded ScAlN initiation layer is shown to reduce the FWHM and tensile stress magnitude, while yielding a film with rms roughness as low as 0.57 nm and no detectable anomalously oriented grains on the sample surface.