Heteroepitaxial B12As2 on silicon substrates

Abstract

The morphology and crystal structure of rhombohedral B[subscript 12]As[subscript 2] thin films prepared by chemical vapor deposition on Si (100), Si (110) and Si (111) substrates were examined. For short depositions, 30 seconds at 1300 °C, the B[subscript 12]As[subscript 2] nucleated in patterns that were unique to each substrate orientation, probably due to variations in the surface atomic structure and surface activation energy of the substrates. Small square domains, one dimensional straight lines, and irregular lines were the representative morphologies on Si (100), Si (111) and Si (110), respectively. For long deposition, 30 minutes at 1300 °C, continuous thin films of B[subscript 12]As[subscript 2] formed with distinct morphologies also dependent on the orientation of the substrates. “Cross”, “wire” and “chain” morphologies were formed on the Si (100), Si (111) and Si (110) substrates, respectively. X-ray diffraction showed that the B[subscript 12]As[subscript 2] films had the following predominant oriented textures: B[subscript 12]As[subscript 2] (110) on Si(100), B[subscript 12]As[subscript 2] (101) on Si(111), and B[subscript 12]As[subscript 2] (001) on Si(110). The in-plane orientations of the B[subscript 12]As[subscript 2] films as determined by XRD pole figures, is also reported.