Solid-source vapor growth and optoelectronic properties of arsenic-based layered group-IV monopnictides

Abstract

We investigated the preparation of SiAs and GeAs films using solid-source vapor growth. The shapes of the SiAs and GeAs films were rectangular, reflecting the thermally stable monoclinic phase (C2/m) along the [010] and [201] axes defining the zigzag and armchair sides. The in-plane crystal orientation of rectangular films can be determined by analyzing the intensities of the active vibrational modes based on the rotation angle. In addition to arsenic-based layered IV–V compounds, SiP films could be grown; therefore, we investigated the alloying of SiAs and SiP. Under As-rich or P-poor conditions, SiAsP rectangular films were grown with three different compositions (As: 0.74–0.69, P: 0.26–0.31). Peak shifts in the Raman modes were observed as the composition changed. The electronic transport of SiAs and GeAs films was demonstrated using a bottom-gate field-effect transistor. The anisotropic factor of the in-plane mobility for the SiAs film was confirmed to be 2.7. The thickness dependence of the in-plane mobility was revealed for the GeAs films owing to the increase in ionized impurity scattering and the effect of contact resistance. Most notably, photoluminescence at peak energies of 2.35 and 2.12 eV could be obtained for the SiAs and GeAs films, respectively. Novel perspectives are opened from the availability of arsenic-based layered IV–V compounds in the field of two-dimensional materials for device applications.