Author
Leigh T. Canham
Other affiliations: Defence Research Agency, Defence Science and Technology Laboratory, University of St Andrews
Bio: Leigh T. Canham is an academic researcher from University of Birmingham. The author has contributed to research in topics: Porous silicon & Silicon. The author has an hindex of 42, co-authored 160 publications receiving 18268 citations. Previous affiliations of Leigh T. Canham include Defence Research Agency & Defence Science and Technology Laboratory.
Papers published on a yearly basis
Papers
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TL;DR: In this article, secondary ion mass spectroscopy (SIMS) analysis is used for the first time to simultaneously monitor all the major impurities on a surface of a Si surface.
Abstract: Microporous and mesoporous Si layers contain a very large surface area that affects both their optical and electrical properties. Secondary ion mass spectroscopy (SIMS) analysis is used for the first time to simultaneously monitor all the major impurities on that surface. SIMS data on a microporous layer demonstrate that its chemical composition changes dramatically with time during ambient air exposure. Similar trends are observed for mesoporous layers. Extended storage in air at room temperature converts the hydride surface of freshly anodized layers to that of a contaminated native oxide. Characterization techniques need to take the metastability of the hydride surface into account since the structural, optical, and electrical properties of porous Si can consequently change with time upon exposure to ambient air. Low‐temperature photoluminescence and spectroscopic ellipsometry data on freshly anodized and ‘‘aged’’ microporous and mesoporous layers are chosen to illustrate typical changes in optical pro...
349 citations
TL;DR: In this article, large wavelength shifts have been measured in the reflectivity spectra of Bragg mirrors etched in porous silicon after exposure of the mirrors to vapor from organic solvents.
Abstract: Large wavelength shifts have been measured in the reflectivity spectra of Bragg mirrors etched in porous silicon after exposure of the mirrors to vapor from organic solvents. The shift in the Bragg wavelength of the mirror arises from refractive index changes, induced by capillary condensation of the vapor in the mesoporous silicon, in the layers of the mirrors. Modeling of the reflectivity changes shows that the layer liquid volume fraction occurring in the measurements was 0.29 for acetone and 0.33 for chlorobenzene. Time-resolved measurements show that condensation occurs on the time scale of tens of seconds.
341 citations
TL;DR: In this article, Lewis acid mediated hydrosilylation of alkynes and alkenes on non-oxidized hydride-terminated porous silicon derivatizes the surface with alkenyl and alkyl functionalities, respectively.
Abstract: Lewis acid mediated hydrosilylation of alkynes and alkenes on non-oxidized hydride-terminated porous silicon derivatizes the surface with alkenyl and alkyl functionalities, respectively. A very broad range of chemical groups may be incorporated, allowing for tailoring of the interfacial characteristics of the material. The reaction is shown to protect and stabilize porous silicon surfaces from atmospheric or direct chemical attack without compromising its valuable material properties such as high porosity, surface area and visible room-temperature photoluminescence. The reaction is shown to act on alkenes and alkynes of all possible regiochemistries (terminal and internal alkynes; mono-, cis- and trans-, di-, tri-, and tetrasubstituted alkenes). FTIR as well as liquid- and solid-state NMR spectroscopies show anti-Markovnikov addition and cis stereochemistry in the case of hydrosilylated terminal alkynes. Material hydrosilylated with long-chain hydrophobic alkynes and alkenes shows a substantially slower surface oxidation and hydrolysis rate in air as monitored by long-term FTIR monitoring and chemography. BJH and BET measurements reveal that the surface area and average pore size of the material are reduced only slightly after hydrosilylation, indicating that the porous silicon skeleton remains intact. Elemental analysis and SIMS depth profiling show a consistent level of carbon incorporation throughout the porous silicon which demonstrates that the reaction occurs uniformly throughout the depth of the film. The effects of functionalization on photoluminescence were investigated and are shown to depend on the organic substituents.
308 citations
TL;DR: A porous silicon membrane may have value as a biomaterial that can support the delivery of cells to the ocular surface and improve existing therapeutic options in patients with corneal epithelial stem cell dysfunction and ocularsurface disease.
296 citations
TL;DR: In this article, the authors investigated the release of Si(OH) 4 from porous Si films under physiological conditions with the aim of developing a bioavailable form of Si, which is vital for normal bone and connective tissue homeostasis.
Abstract: Silicon (Si) in the form of orthosilicic acid (Si(OH) 4 ) is vital for normal bone and connective tissue homeostasis. Porous Si films release Si(OH) 4 in aqueous solutions in the physiological pH range. This study investigates the release of Si(OH) 4 from porous Si films under physiological conditions with the aim of developing a bioavailable form of Si. Using a standardised technique, porous Si films released increasing Si with time. Dissolution was significant at pH 7 and above, and at a temperature of 37 °C. Higher porosity generally promoted dissolution, however multiple layer films did not show enhanced solubility over corresponding single layer controls. These properties will be used to optimise Si nanostructures that slowly deliver orthosilicic acid in the digestive tract.
223 citations
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TL;DR: In this article, the authors focus on the properties of quantum dots and their ability to join the dots into complex assemblies creates many opportunities for scientific discovery, such as the ability of joining the dots to complex assemblies.
Abstract: 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.
10,737 citations
TL;DR: Dye-sensitized solar cells (DSCs) offer the possibilities to design solar cells with a large flexibility in shape, color, and transparency as mentioned in this paper, and many DSC research groups have been established around the world.
Abstract: 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 ...
8,707 citations
TL;DR: This observation shows that quantum confinement in layered d-electron materials like MoS(2), a prototypical metal dichalcogenide, provides new opportunities for engineering the electronic structure of matter at the nanoscale.
Abstract: 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.
7,886 citations
TL;DR: In this article, the authors present methods of severe plastic deformation and formation of nanostructures, including Torsion straining under high pressure, ECA pressing, and multiple forging.
5,763 citations
TL;DR: Nanotechnology is a multidisciplinary field, which covers a vast and diverse array of devices derived from engineering, biology, physics and chemistry that can provide essential breakthroughs in the fight against cancer.
Abstract: 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.
4,241 citations