Laser Assisted Direct Local Synthesis of Semiconducting Nanowires

摘要: Semiconductor nanowires have been in the spotlight, carrying great promise for realization of future generation devices spanning diverse fields including electronics and photonics, biotechnology, energy conversion storage. In order to realize these functionalities, new techniques must be developed that will enable precise layout assembly homogenous or heterogeneous components into functional superblocks. This thesis puts forward laser assisted direct localized growth as a promising route synthesis semiconductor has previously hard achieve.Laser considered versatile efficient tool micro- nano-structure fabrication several decades. By taking advantage rapid spatially confined heating capabilities radiation, nanostructures can synthesized only within high temperature region over threshold processing temperature. The surroundings structure hence remains at room temperature, allowing minimization damage various device lie on wafer platform. addition, via capability, nanoscale materials grown with an arbitrary position accuracy.In this study, silicon nanowire (SiNW) is explored using assembled gold nanoparticles (AuNPs) thin film. Continuous wave (CW) illumination employed 514 nm wavelength different direction. Parametric study carried out by controlling process conditions such time, power, direction, which demonstrates laser-assisted process. Film-side favorable catalysts through plasmonic resonance allows one-dimensional (1-D) very early stage. However, subsequent dominated secondary deposition pre-grown portion nanowires. On contrary, substrate-side enabling indirect light absorbing layer amorphous film thicker than optical penetration depth radiation leads stable controlled Although kinetic analysis confirms behavior follows usual Arrhenius trend, it shown rate faster conventional furnace based possibly due three-dimensional diffusion reactant gases hot spot.Motivated fast capability temporal resolution, detailed investigation mechanism SiNWs diameter- temperature-dependence nucleation catalyst diameter dependence activation solid Au. From investigation, confirmed technique comprises systematic explore nano-synthesized materials.To SiNWs-based devices, also important grow them arrange, assemble as-grown existing device. most date face problems their low yield insufficient spatial resolution. two methods are proposed more semiconducting prescribed without post-process alignment assembly. One employ near-field probe coupled laser. Confined beam beyond diffraction limit employing probes source realizes single SiNW from specific particle among randomly distributed separated nanometric distances AuNPs substrate. other electrically biased sharp tip, focused well highly selective growth. It demonstrated short aligned along direction induced electric field pulling (AuNP) same thanks strongly enhanced electrostatic force tip. examined driving As calibration step, deflection tip respect applied bias voltage measured quantified Hook's law.