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Excited electron lifetime in silicon nanoparticles
The goal of this semester thesis is to acquire a statistic of the carrier lifetime of different sized SiNP, which are then compared to the bulk carrier lifetime of silica.
Silicon nanoparticles are interesting scatterers in the optical regime due to their high refractive
index, giving rise to the rich physics of Mie scattering for rather small particle diameters [1]. While the synthesis of Si nanoparticles of high quality has been challenging until recently, these materials are now available and can be investigated and put to use by the photonics community [2]. The high surface-to-bulk ratio and the geometrical confinement, as in nanoparticles, often leads to different properties as compared to bulk material. One of these properties is the carrier lifetime after optical excitation by a short laser pulse. The ultra-fast optical response of these particles is governed by the decay of excited electrons.
The goal of this semester thesis is to acquire a statistic of the carrier lifetime of different sized SiNP, which are then compared to the bulk carrier lifetime of silica. You will start by fabrication of a sample, that allows to measure individual SiNPs. You will characterize the sample geometry by means of atomic force microscopy and measure the carrier lifetime in a state-of-the-art time-domain pump-probe setup. You should have a solid understanding of optics and interest to learn the basics of sample fabrication and characterization. Furthermore you should have basic knowledge of data analysis. You should have a quantitative approach and be a critical and independent thinker who enjoys to contribute to a larger research effort of a team.
References:
[1] Sugimoto et al., Adv. Opt. Mat. 8, 200033
[2] Thiessen et al., Chem. of Mat. 31, 678
Prerequisites:
Good knowledge of and strong interest in optics and electronics, practical lab skills,
quantitative approach.
Silicon nanoparticles are interesting scatterers in the optical regime due to their high refractive index, giving rise to the rich physics of Mie scattering for rather small particle diameters [1]. While the synthesis of Si nanoparticles of high quality has been challenging until recently, these materials are now available and can be investigated and put to use by the photonics community [2]. The high surface-to-bulk ratio and the geometrical confinement, as in nanoparticles, often leads to different properties as compared to bulk material. One of these properties is the carrier lifetime after optical excitation by a short laser pulse. The ultra-fast optical response of these particles is governed by the decay of excited electrons. The goal of this semester thesis is to acquire a statistic of the carrier lifetime of different sized SiNP, which are then compared to the bulk carrier lifetime of silica. You will start by fabrication of a sample, that allows to measure individual SiNPs. You will characterize the sample geometry by means of atomic force microscopy and measure the carrier lifetime in a state-of-the-art time-domain pump-probe setup. You should have a solid understanding of optics and interest to learn the basics of sample fabrication and characterization. Furthermore you should have basic knowledge of data analysis. You should have a quantitative approach and be a critical and independent thinker who enjoys to contribute to a larger research effort of a team.
References: [1] Sugimoto et al., Adv. Opt. Mat. 8, 200033 [2] Thiessen et al., Chem. of Mat. 31, 678
Prerequisites: Good knowledge of and strong interest in optics and electronics, practical lab skills, quantitative approach.