Si/SiO2 Core/Shell Luminescent Silicon Nanocrystals and Porous Silicon Powders With High Quantum Yield, Long Lifetime, and Good Stability

Gelloz, Bernard; Juangsa, Firman Bagja; Nozaki, Tomohiro; Asaka, Kinji; Koshida, Nobuyoshi; Jin, Lianhua

doi:10.3389/fphy.2019.00047

Cited by 31 publications

(24 citation statements)

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“…Therefore, the PL of nanocrystalline porous silicon (por-Si) is sensitive to the nanocrystal size, as well as the surface termination [25]. The long radiative lifetime of nanocrystalline silicon [26] leads to an unusually important competition between radiative and non-radiative processes, which greatly complicates a mechanistic understanding of its photoluminescence [27][28][29]. The natural hydrogen termination of as-formed por-Si is extremely efficient at passivating electron-hole pair recombination centers [30], for powders, especially for very small particles sizes and large volumes.…”

Section: Introductionmentioning

confidence: 99%

Response of Photoluminescence of H-Terminated and Hydrosilylated Porous Si Powders to Rinsing and Temperature

et al. 2020

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The photoluminescence (PL) response of porous Si has potential applications in a number of sensor and bioimaging techniques. However, many questions still remain regarding how to stabilize and enhance the PL signal, as well as how PL responds to environmental factors. Regenerative electroless etching (ReEtching) was used to produce photoluminescent porous Si directly from Si powder. As etched, the material was H-terminated. The intensity and peak wavelength were greatly affected by the rinsing protocol employed. The highest intensity and bluest PL were obtained when dilute HCl(aq) rinsing was followed by pentane wetting and vacuum oven drying. Roughly half of the hydrogen coverage was replaced with –RCOOH groups by thermal hydrosilylation. Hydrosilylated porous Si exhibited greater stability in aqueous solutions than H-terminated porous Si. Pickling of hydrosilylated porous Si in phosphate buffer was used to increase the PL intensity without significantly shifting the PL wavelength. PL intensity, wavelength and peak shape responded linearly with temperature change in a manner that was specific to the surface termination, which could facilitate the use of these parameters in a differential sensor scheme that exploits the inherent inhomogeneities of porous Si PL response.

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Section: Introductionmentioning

confidence: 99%

Response of Photoluminescence of H-Terminated and Hydrosilylated Porous Si Powders to Rinsing and Temperature

et al. 2020

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“…As a result, freestanding SiNCs with a narrow size distribution (a mean size of 6 nm) was produced for various applications. [ 6,22 ]…”

Section: Experimental Methodsmentioning

confidence: 99%

Interfacial region effect on thermal conductivity of silicon nanocrystal and polystyrene nanocomposites

Juangsa

Ryu

Morikawa

et al. 2020

Plasma Processes & Polymers

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Thermal transport has been widely studied in nanosize materials owing to their unique properties, including size-dependent thermal transport properties. Bulksize nanostructures are often used for thermal property investigation as well as device applications. The nanocomposite structure of silicon nanocrystals (SiNCs) and polystyrene (PS) has been reported to have a significant thermal transport suppression attributed to the thermal resistance at material interfaces. Although the theoretical effective medium approximation (EMA) model for nanocomposites considers the thermal boundary resistance, a constant deviation is observed between the model and measurement results. In this study, the thermal transport of a polymer, which is known to be morphology dependent, is investigated in a region near the interfacial boundary. Nanocomposites were fabricated from SiNCs with significantly different diameters (6 and 60 nm), and their thermal conductivity was measured to analyze the effect of particle size on the effective thermal conductivity and its deviation. The results showed that the interfacial region of the PS matrix significantly affects the thermal transport, and the EMA model can be enhanced by modifying the thermal conductivity of the matrix owing to the confinement effect at the interfacial region; and the model and measurement results are in good agreement. This study shows that the interaction at material interfaces and its effect on the interfacial region play an important role in determining the thermal transport, opening up the possibility of controlling the thermal transport properties for wide applications of polymerbased nanocomposite devices. K E Y W O R D Sinterfacial region, nanocomposite, silicon nanocrystals, thermal transport

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“…As a result visible room temperature luminescence is routinely observed in PS and Si-NC. Surface treatments improve the quantum yields by surface passivation [28] up to values of almost 100% at low temperatures [29].…”

Section: Porous Siliconmentioning

confidence: 99%

Thirty Years in Silicon Photonics: A Personal View

Pavesi

2021

Front. Phys.

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Silicon Photonics, the technology where optical devices are fabricated by the mainstream microelectronic processing technology, was proposed almost 30 years ago. I joined this research field at its start. Initially, I concentrated on the main issue of the lack of a silicon laser. Room temperature visible emission from porous silicon first, and from silicon nanocrystals then, showed that optical gain is possible in low-dimensional silicon, but it is severely counterbalanced by nonlinear losses due to free carriers. Then, most of my research focus was on systems where photons show novel features such as Zener tunneling or Anderson localization. Here, the game was to engineer suitable dielectric environments (e.g., one-dimensional photonic crystals or waveguide-based microring resonators) to control photon propagation. Applications of low-dimensional silicon raised up in sensing (e.g., gas-sensing or bio-sensing) and photovoltaics. Interestingly, microring resonators emerged as the fundamental device for integrated photonic circuit since they allow studying the hermitian and non-hermitian physics of light propagation as well as demonstrating on-chip heavily integrated optical networks for reconfigurable switching applications or neural networks for optical signal processing. Finally, I witnessed the emergence of quantum photonic devices, where linear and nonlinear optical effects generate quantum states of light. Here, quantum random number generators or heralded single-photon sources are enabled by silicon photonics. All these developments are discussed in this review by following my own research path.

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Si/SiO2 Core/Shell Luminescent Silicon Nanocrystals and Porous Silicon Powders With High Quantum Yield, Long Lifetime, and Good Stability

Cited by 31 publications

References 50 publications

Response of Photoluminescence of H-Terminated and Hydrosilylated Porous Si Powders to Rinsing and Temperature

Response of Photoluminescence of H-Terminated and Hydrosilylated Porous Si Powders to Rinsing and Temperature

Interfacial region effect on thermal conductivity of silicon nanocrystal and polystyrene nanocomposites

Thirty Years in Silicon Photonics: A Personal View

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