Controlled Synthesis of GaSb Nanowires Based on CVD-grown and Their Optical Characterization

Abstract

Gallium antimonide (GaSb) has a relatively narrow band gap, high electron mobility and excellent saturation velocity, in addition, p-type GaSb nanowires (NWs) can be integrated with n-type nanowire devices potentially. These properties make it applicable both optically and electrically. However, it is noted that the radial dimensions and crystal quality have remarkable influence on the performance of photovoltaic devices. Based on traditional CVD technology, the influence of Au nanoparticles on Vapoure-Liquide-Solid (VLS) growth mechanisms has been studied, GaSb nanowires grown on two different substrates which undergo gold sputtering and gold solution dropping treatment have different geometries of seed particle on nanowire tip and shapes of its body, moreover, the contact angle between these two parts provides stable condition for nanowires growth which has considerable impact on growth direction. The entire growing process is divided into three phases by the temperature: the heating phase, the synthesis phase and the cooling phase. Controllable synthesis has been realized by fixing the synthesis temperature at 900 ℃ and keeping the other factors unchanged. In the meantime, changing the synthesis time from 60 minutes to 240 minutes in steps, it is found that the breakthrough in radial dimensions and specific surface has been realized with the increase of growing time, the GaSb nanowire of 50 µm has been achieved in this paper. Furthermore, the nanowires were systematically characterized by scanning electron microscope (SEM), transmission electron microscope (TEM) and X-ray diffraction (XRD), which suggest that this material has the zincblende structure with good crystal quality and high purity. Also, the Multi-mode phonon oscillation and band-edge emission of the nanowires are shown through Raman spectroscopy (Raman) and Photoluminescence Spectroscopy (PL). All these demonstrate the superior surface morphology and good crystallinity of the obtained nanowires. The study makes contribution to the extensive exploration and novel discoveries of precise controllable growth of GaSb nanowires.