Size dependence of the quantum yield of photoluminescence from silicon nanocolloids

Abstract

We have prepared several nanometer-sized silicon colloids in the range from 3.7 to 9.8 nm with a constant weight density 1 mg/ml. The blue-green emission is found to be independent of size contrast to its intensity. The absolute quantum yield as a function of size is determined. From the proposed model that combines surface as well as volume effects, the emission is proved to be from a surface trapped site. The energy transfer efficiency from volume to the site is almost 100% for the 3.7 nm particle.

Synthesis of Luminescent Silicon Nanopowders Redispersible to Various Solvents

“…On the other hand, no emission can be detected when excited by low energetic photons located between 400 nm to 500 nm. Since UV excitation energy corresponds to direct band gap absorption in medium sized Si nanoparticles (4−10 nm), upon irradiation with the UV photons, excited carriers due to direct band gap absorption are prone to relax into many kinds of states with lower energy, such as indirect band edge, unsaturated Si atoms on surfaces, or other defects existing in Si cores, Si/oxide interfaces, or oxide phases. , As shown by XRD patterns in Figure , our annealed powders consist of amorphous silicon oxides and Si particles. A large amount of defects are supposed to exist in these materials.…”

Enhanced Photoluminescence from Si Nano-organosols by Functionalization with Alkenes and Their Size Evolution

“…Due to the relative easiness of producing PS by etching silicon wafers, there have been many studies of optical properties of PS, but low efficiency and instability of the photoluminescence from PS inhibit their further fundamental investigation and commercial applications. The PL intensity of PS is mainly limited by nonradiative carrier recombination on defects produced during the etching process, and the poor PL stability of PS is mainly owing to the generation of nonradiative defects at the initially hydrogen-terminated nanocrystalline Si surface upon oxidation during storage in air. To enhance the PL intensity of PS, some oxidation techniques such as electrochemical or thermal processing have been attempted. − Meanwhile, to enhance the red-band luminescence stability, many groups have carried out chemical modifications of the PS surface to replace the initial metastable Si−H bonds on nanocrystalline Si surfaces by stable covalent Si−C bonds.…”

Investigation of structure and properties of nanocrystalline silicon on various buffer layers

“…Furthermore, in 1990, silicon-based visible light emission devices were stimulated by electrochemically prepared porous Si; 7 and this study was followed by many others concerning this topic. [8][9][10][11] Therefore, the nc-Si thin film has become an important and interesting material in microelectronic or optoelectronic applications. In the past, the nc-Si thin films were usually deposited on glass or silicon substrate, so very few studies focused on the properties of nc-Si films deposited on other layers, such as Si 3 N 4 , a-Si, and SiO 2 .…”