Synthesis, morphology and compositional evolution of silicon nanowires directly grown on SnO₂ substrates

We here propose an all-in situ method for growing vapor-liquid-solid (VLS) silicon nanowires (SiNWs) directly on SnO₂ substrates in a plasma-enhanced chemical vapor deposition system. The tin catalysts are formed by a well-controlled H₂ plasma treatment of the SnO₂ layer. The lowest temperature for the tin-catalyzed VLS SiNWs growth in a silane plasma is ∼250°C. The effects of substrate temperature and H ₂ dilution of silane on the morphology and compositional evolution of the SiNWs were systematically investigated. The catalyst content in the SiNWs can be effectively controlled by the deposition temperature. Moreover, enhanced absorption (down to ∼1.1 eV) is achieved due to the strong light trapping and anti-reflection effects in the straight and long tapered SiNWs.