Controlled faceting and morphology for light trapping in aluminum-catalyzed silicon nanostructures

Aluminum-catalyzed silicon nanopyramids grown using low-pressure chemical vapor deposition (LPCVD) are presented as an approach to silicon surface texturing. The nanopyramids are grown by vapor-liquid-solid growth using aluminum thin films on silicon. Silicon nanowires with hexagonal cross sections are formed at a growth temperature of 650 degrees C; as the temperature is increased to 700 degrees C, the wires become pyramid-shaped with triangular cross-sections. The silicon nanopyramids are single crystal and grow in the direction with (112) facets, as confirmed by transmission electron microscopy. Pyramid tapering increases with increasing growth temperatures and the pyramid arrays grown at 700 C show refiectivities between 4 and 6% between 400 nm and 800 nm and appear black to the eye. Based on these results, aluminum-catalyzed nanopyramids present themselves as a plausible alternative to etch-based silicon surface textures. (C) 2016 Elsevier B.V. All rights reserved.