Epitaxial growth of silicon nanowire arrays at wafer-scale using high-speed rotating-disk CVD for improved light-trapping

Abstract

Silicon nanowires (Si-NWs) have been fabricated at wafer-scale with Au nanoparticles as catalysts at 500 °C using a chemical-vapor-deposition (CVD) method combined with a high-speed rotation wafer-disk. High resolution TEM and SAED patterns were used to characterize the microstructures of the grown Si-NWs. Single crystalline Si-NWs appear self-oriented on Si (100) substrates along the <111> growth axis. The nanowires have a uniform diameter of 50 nm and varying lengths and densities depending on the rotation speed of the wafer substrate. The effects of wafer-rotation speed on the growth of Si-NWs are discussed. Due to a reduced boundary layer thickness, fast mass transport leads to both an enhanced growth rate and density of the Si-NWs. Moreover, the density of the Si-NW array is optimized to achieve a low reflectance loss for their further application in tandem solar cells as the light-trapping layer.