PATTERNED GROWTH OF Si NANOWIRES: A COMPARATIVE STUDY OF VLS AND SLS

Abstract

In this paper, we report morphology of silicon nanowires ( Si - NWs ) grown on various surfaces and patterned substrates using Vapor–Liquid–Solid (VLS) and Solid–Liquid–Solid (SLS) techniques. It is observed that the growth conditions are critical in controlling the dimensions of wires in both techniques. In addition to this, it is also demonstrated that Si - NWs are essentially different grown on Si or GaAs substrates. For growth of Si - NWs by VLS, Si powder was evaporated in a tube furnace under Ar flow while substrates were kept at different temperatures. In SLS, experimental conditions were identical except that no external source was used. Si - NWs thus grown showed dependence on the flow rate of Ar gas and the temperature of the substrate. Interestingly, instead of only radial nannowires (NWs), nanobelts and tapered NWs were also grown on patterned Au -catalyzed GaAs surface. In the end, the analysis on the basis of existing theories of NW growth is presented. Optical properties of Si - NWs are also briefly discussed.