Current research into semiconductor clusters is focused on the properties of quantum dots-fragments of semiconductor consisting of hundreds to many thousands of atoms-with the bulk bonding geometry and with surface states eliminated by enclosure in a material that has a larger band gap. Quantum dots exhibit strongly size-dependent optical and electrical properties. The ability to join the dots into complex assemblies creates many opportunities for scientific discovery.

Semiconductor Clusters, Nanocrystals, and Quantum Dots

Dye-sensitized solar cells (DSCs) offer the possibilities to design solar cells with a large flexibility in shape, color, and transparency. DSC research groups have been established around the worl ...

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Dye-Sensitized Solar Cells

Novel physical phenomena can emerge in low-dimensional nanomaterials. Bulk MoS2, a prototypical metal dichalcogenide, is an indirect bandgap semiconductor with negligible photoluminescence. When the MoS2 crystal is thinned to monolayer, however, a strong photoluminescence emerges, indicating an indirect to direct bandgap transition in this d-electron system. This observation shows that quantum confinement in layered d-electron materials like MoS2 provides new opportunities for engineering the electronic structure of matter at the nanoscale.

Emerging Photoluminescence in Monolayer MoS2

Bulk nanostructured materials from severe plastic deformation

Nanotechnology is a multidisciplinary field, which covers a vast and diverse array of devices derived from engineering, biology, physics and chemistry. These devices include nanovectors for the targeted delivery of anticancer drugs and imaging contrast agents. Nanowires and nanocantilever arrays are among the leading approaches under development for the early detection of precancerous and malignant lesions from biological fluids. These and other nanodevices can provide essential breakthroughs in the fight against cancer.

Cancer nanotechnology: opportunities and challenges.

The effect of the chemical thinning of the porous silicon structure on the speed and efficiency of electroluminescent devices, produced by the anodisation of a pn junction in bulk silicon is investigated. Thinning of the silicon wires results in an increase in the efficiency but at the expense of a reduction in operating speed. It is demonstrated that the operating speed is limited by the photoluminescence lifetime for small signal excitation. However, for large signals, the electroluminescence can be turned off more than 5 times faster than the photoluminescence lifetime, indicating that this need not necessarily limit device operating speed.

A Study of the Factors Which Determine the Modulation Speed of a Shallow PN Junction Porous Silicon Led

We performed interferometric time-resolved simultaneous reflectance and transmittance measurements to investigate the carrier dynamics in pump-probe experiments on thin porous silicon membranes. The experimental data was analysed by using a method built on the Wentzel-Kramers-Brillouin approximation and the Drude model, allowing us to reconstruct the excited carriers’ non-uniform distribution in space and its evolution in time. The analysis revealed that the carrier dynamics in porous silicon, with ~50% porosity and native oxide chemistry, is governed by the Shockley-Read-Hall recombination process with a characteristic time constant of 375 picoseconds, whereas diffusion makes an insignificant contribution as it is suppressed by the high rate of scattering.

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Reconstructing charge-carrier dynamics in porous silicon membranes from time-resolved interferometric measurements

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Communication—Supercritically-Dried Membranes and Powders of >90% Porosity Silicon with Pore Volumes Exceeding 4 cm3 g−1

Chapter headings and selected papers: Preface Invited Papers Radiative processes in bulk crystalline silicon (G Davies) Different Er centres in Si and their use for electroluminescent devices (W Jantsch et al) Field-induced functions of porous Si as a confined system (N Koshida et al) Porous Silicon Strongly nonlinear luminescence in oxidized porous silicon films (H Koyama et al) Laser assisted chemical vapour deposition of silicon oxide layers (P Paiva et al) Application of stain-etched porous silicon in light emitting diodes and solar cells (D Dimova-Malinovska) Silicon and Germanium Nanocrystals Size dependent photoluminescence from Si nanoclusters produced by laser ablation (L Patrone et al) Light emitting diode structure based on Si nanocrystals formed by implantation into thermal oxide (N Lalic, J Linnros) Rare Earth in Silicon and Related Materials EPR study of erbium-impurity complexes in silicon (JD Carey et al) Er-doped edge emitting devices with a SiGe waveguide (C-X Du et al) Erbium in silicon-germanium quantum wells (AT Naveed et al) Si-based Alloys, Multilayers and Hydrogenated a-Si XPS investigation of a-Si: H thin films after light soaking (A Toneva et al) Light Emitting Silicides Electronic and optical properties of semiconducting iron disilicide (AB Filonov et al) SiGe Structures and Ge Islands Room-temperature SiGe light-emitting diodes (L Vescan, T Stoica) Other Light Emitting Structures Black-body emission from nanostructured materials (P Roura et al) List of contributors Subject index Material index

Light Emission from Silicon: Progress Towards Si-Based Optoelectronics

Porous silicon particles could be utilized in a variety of consumer care applications if their cost of manufacture becomes low enough. Silica and porous silica are already widely used by the toothpaste and cosmetic industries, and porous silicon offers superior mechanical properties for teeth cleaning and very different optical properties for cosmetics. Partial thermal oxidation has been used to improve shelf life in liquid formulations and to match brown skin tones. Preliminary mouthfeel testing for oral hygiene products has been carried out, but formalized skin-feel testing and optimization is required for numerous dermatological products. Product examples discussed include multifunctional dentifrice abrasives, sunscreens, bronzers, foundation and makeup additive, and anti-aging formulations. L. Canham (*) pSiMedica Ltd., Malvern Hills Science Park, Malvern, Worcester, UK e-mail: lcanham@psivida.com # Springer International Publishing Switzerland 2014 L. Canham (ed.), Handbook of Porous Silicon, DOI 10.1007/978-3-319-05744-6_102 999

http://link.springer.com/content/pdf/10.1007%2F978-3-319-05744-6_102.pdf

Leigh T. Canham

Papers

A Study of the Factors Which Determine the Modulation Speed of a Shallow PN Junction Porous Silicon Led

Reconstructing charge-carrier dynamics in porous silicon membranes from time-resolved interferometric measurements

Communication—Supercritically-Dried Membranes and Powders of >90% Porosity Silicon with Pore Volumes Exceeding 4 cm3 g−1

Light Emission from Silicon: Progress Towards Si-Based Optoelectronics

Porous Silicon for Oral Hygiene and Cosmetics