Synthesis of Light-Absorbing ZnSnP2 Semiconductor Nanowires

Thursday, 28 May 2015: 09:20
Conference Room 4D (Hilton Chicago)
S. Lee, J. Gu, E. Fahrenkrug, and S. Maldonado (University of Michigan)
The conjecture of ZnSnP2 semiconductor nanowires as promising inexpensive solar absorber and the nanowire preparation method was discussed in this presentation. Single-phase crystalline ZnSnP2 nanowires have been prepared via simple chemical-vapor-deposition (CVD) of Zn and SnP3 powder in a custom-built tube furnace reactor, allowing the vapors to react with thermally evaporated Sn islands on 40 mm2 Si(111) substrate. Powder X-ray diffraction data and Raman scattering of the nanowire films, along with single-nanowire analysis using high-resolution transmission electron microscope (HRTEM) indicate that the as-prepared ZnSnP2 nanowires possess single-crystalline sphalerite structure, as opposed to the antisite defect-free chalcopyrite structure. Nonetheless, the nanowires show homogenous elemental distribution of Zn, Sn, and P, with chemical composition close to the 1:1:2 stoichiometric ratio. Photoelectrochemical measurements in aqueous electrolyte show the as-prepared ZnSnP2 nanowires exhibit stable cathodic photoresponse under white light illumination. Tapered nanowires that lead to formation of Zn3P2 nanowires dominate at extended growth duration, implying the Sn islands serve both as the vapor-liquid-solid (VLS) growth seed and sole contributor of Sn. Approaches to minimize consumption of Sn will be presented to ensure production of long nanowire with consistent diameter. This study presents a benign and straightforward approach to prepare single-phase Zn-IV-P2 nanowires suitable for energy conversion applications.