Growth of highly (0001)-oriented aluminum nitride thin films with smooth surfaces on silicon carbide by gas-source molecular beam epitaxy

Abstract Aluminum nitride thin films with very smooth surfaces have been grown by gas-source molecular beam epitaxy on 4H and 6H silicon carbide substrates. High purity ammonia was used as the nitrogen source in conjunction with Al evaporated from an effusion cell. Streaked reflection high energy electron diffraction patterns and reconstructions of the AlN surfaces indicated smooth films. This surface character was confirmed via atomic force microscopy and transmission electron microscopy which showed roughness root mean square values typically below 1 nm and very flat surfaces, respectively. X-ray diffraction showed the films to be highly c -axis oriented and single phase. Major impurities in the AlN films were oxygen and carbon, as revealed by secondary ion mass spectrometry.