Silicon Nanophotonics
Synthesis and Optical Properties of Silicon Nanowires
Students: AlexGuichard, LinyouCao, RohanKekatpure
Synthesis of Si nanowires
- Most established: Vapor-Liquid-Solid Mechanism (VLS)
- Au nanoparticles catalyze the decomposition of SiH_4 gas
- Au and Si form a liquid phase alloy above the eutectic temperature
- Decomposition of SiH_4 causes a supersaturation of the Au/Si alloy particle
- Si nanowires grow from the supersaturated alloy
- Au nanoparticle size determines the diameter of the nanowire
- Au is a deep trap in Si, causing fast non-radiative decay!
Other materials can act as growth catalysts
Nanowire furnace with flashlamp heating
Light emission from oxidized TiSi2- and Co-catalyzed wires
- Oxidation shrinks wire core diameter, induces confinement
- passivates Si wire surface
- PL decay lifetimes are roughly 10 us
- Emission consistent with emission from Quantum confinement of carriers in the crystalline Si nanowire core.