Excitation of size selected nanocrystallites in porous silicon

Abstract

We prepared silicon that exhibits green-to-red rainbow luminescence along the sample, reflecting gradients in the crystallite size. The excitation has a size-dependent feature, riding a smooth bulklike continuum. For the size-dependent contribution, we measured absorption band edges of 3.75 and 3.0–3.25 eV at the meniscus and opposite end. Excitation in the meniscus, monitored at the edge of the blue emission, isolates ultrasmall sizes, with “excitation coefficients” quadratic with energy, and emission encompassing much of the visible spectrum. Results are discussed in terms of quantum-confinement-induced restructuring of the diamondlike bonds to form radiative Si–Si surface states.

Detection of luminescent single ultrasmall silicon nanoparticles using fluctuation correlation spectroscopy

“…The smallest structure is found where the anodizing current concentrates, such as at the meniscus ͑air-liquid interface͒. 7,8,3 The ultrasmall particles are enriched by advancing the wafer, at a speed of ϳ1 mm/h, producing a large meniscus-like area. An ultrasound acetone bath crumbles the top film into a colloid of ultrasmall particles, leaving a deep red luminescent bottom layer.…”

Generation of optically active states in a-SiNx by thermal treatment

“…Because it has lower barriers for electrons and holes than silicon oxide, the operating voltage of silicon nitride in realizing silicon-based LEDs is somewhat low [5]. Most research conducted on silicon nitride-based luminescent materials has mainly focused on optical characteristics using photoluminescence and infrared spectroscopy [8][9][10][11][12].…”

Biocompatible fluorescent silicon nanocrystals for single-molecule tracking and fluorescence imaging

“…Inspired by the work of Yamani et al (1998), Akcakir et al (2000), and Belomoin et al (2002), we developed an easier protocol that specifically generates red-emitting SiNCs (see Materials and methods subsections Preparation of SiNC on the wafer through Recovery and purification of mSiNC; Fig. 1, A-C).…”