VLS growth of Ni Catalyzed Si1-xGex Nanowires

Abstract

One of the most attractive techniques to fabricate semiconducting nanowires is by the Vapor Liquid Solid method (VLS). By means of this Si1-xGex nanowireswere gently grown axially with change in their compositions with a SiCl4: GeCl4 ratio of 2:8, 3:7, 4:6, 5:5, 8:2, 7:3 and 6:4 respectively. The growth was carried out for different times and different temperatures including 1000 oC, 950 oC, 900 oC and 850 oC. It was found that the nanowires were grown successfully vertical on almost all temperatures except at 900 oC and 850 oC, some of the wires were observed as bearing flower like structure. The wires were characterized by high resolution scanning electron microscopy (SEM), high resolution transmission electron microscopy (FESTEM) with EDS facility. It was observed that wires can be grown successfully vertical by changing the inlet flow ratio of precursors and at different temperatures. The wires with equal ratio of precursors, high ratio of SiCl4 and low of GeCl4 and low ratio of SiCl4 and high of GeCl4, were observed under STEM with EDS facility. It was revealed that at high inlet and low input of SiCl4 and GeCl4 respectively, the wire was rich with Si and containing less amount of Ge and vice versa. At an equal ratio of precursors flow, the EDS showed that tip and neck of the wire was rich with germanium while rest of the body was rich with Si.