L. Manin-Ferlazzo

Bio: L. Manin-Ferlazzo is an academic researcher from Centre national de la recherche scientifique. The author has contributed to research in topics: Reactive-ion etching & Electron-beam lithography. The author has an hindex of 4, co-authored 8 publications receiving 1011 citations.

Optical investigation of micrometer and nanometer-size individual GaN pillars fabricated by reactive ion etching

Abstract: We present an optical investigation of GaN pillars using both micro-Raman (μ-Raman) and microphotoluminescence (μ-PL) spectroscopy. GaN pillars of diameter ranging from 100 nm to 5 μm were fabricated by electron beam lithography and reactive ion etching (RIE) with SiCl4 plasma. Optical measurements of both μ-Raman and μ-PL on individual pillars show consistent variations in the properties of the fabricated GaN structures as a function of GaN pillar size. μ-PL mapping gives strong evidence for defect-induced donors and/or acceptors near the facets of the RIE etched pillars. RIE for the nanostructuration of GaN could be used in the future to allow spectroscopic studies of a few or single quantum objects such as GaN quantum dots.

Raman scattering in GaN pillar arrays

Abstract: We present a detailed study of GaN pillar arrays by atomic force microscopy (AFM), Raman spectroscopy, and photoluminescence (PL) spectroscopy. AFM is used to characterize the shape of the GaN pillars and revealed a large roughness of etched pillar surfaces. Raman scattering spectra of the pillars are well described by angular dispersion of polar optical phonons induced by the three-dimensional shape of the pillar. Additional Raman scattering has been tentatively assigned to the activation of the high frequency B1 silent mode by defects introduced during the ion etching. This result is well correlated with the appearance of donor and acceptor-related PL of the GaN pillars. N vacancy or/and Ga interstitials would be likely candidates for donors in the nonstoichiometric GaN near the surface of the etched pillars.

Equifrequency surfaces in GaN/sapphire photonic crystals

Abstract: Photonic crystals are a new class of materials where photonic band gaps, large dispersion and anisotropy occur. By exploiting these properties GaN photonic crystals should have important potential for optoelectronic applications, principally in the areas of high-efficiency light emitters and second-harmonic generators. We present measurements of the equifrequency surfaces of the radiative Bloch modes for a photonic crystal etched in a GaN/sapphire film. The photonic band structure is calculated by using a scattering matrix method that reproduces well the anisotropy of the equifrequency surfaces exhibited by the photonic crystal. (C) 2002 Elsevier Science B.V. All rights reserved.

The control of human mesenchymal cell differentiation using nanoscale symmetry and disorder

Abstract: A key tenet of bone tissue engineering is the development of scaffold materials that can stimulate stem cell differentiation in the absence of chemical treatment to become osteoblasts without compromising material properties. At present, conventional implant materials fail owing to encapsulation by soft tissue, rather than direct bone bonding. Here, we demonstrate the use of nanoscale disorder to stimulate human mesenchymal stem cells (MSCs) to produce bone mineral in vitro, in the absence of osteogenic supplements. This approach has similar efficiency to that of cells cultured with osteogenic media. In addition, the current studies show that topographically treated MSCs have a distinct differentiation profile compared with those treated with osteogenic media, which has implications for cell therapies.

One-dimensional ZnO nanostructures: Solution growth and functional properties

Abstract: One-dimensional (1D) ZnO nanostructures have been studied intensively and extensively over the last decade not only for their remarkable chemical and physical properties, but also for their current and future diverse technological applications. This article gives a comprehensive overview of the progress that has been made within the context of 1D ZnO nanostructures synthesized via wet chemical methods. We will cover the synthetic methodologies and corresponding growth mechanisms, different structures, doping and alloying, position-controlled growth on substrates, and finally, their functional properties as catalysts, hydrophobic surfaces, sensors, and in nanoelectronic, optical, optoelectronic, and energy harvesting devices.

A 160-kilobit molecular electronic memory patterned at 10 11 bits per square centimetre

Abstract: The primary metric for gauging progress in the various semiconductor integrated circuit technologies is the spacing, or pitch, between the most closely spaced wires within a dynamic random access memory (DRAM) circuit. Modern DRAM circuits have 140 nm pitch wires and a memory cell size of 0.0408 mum(2). Improving integrated circuit technology will require that these dimensions decrease over time. However, at present a large fraction of the patterning and materials requirements that we expect to need for the construction of new integrated circuit technologies in 2013 have 'no known solution'. Promising ingredients for advances in integrated circuit technology are nanowires, molecular electronics and defect-tolerant architectures, as demonstrated by reports of single devices and small circuits. Methods of extending these approaches to large-scale, high-density circuitry are largely undeveloped. Here we describe a 160,000-bit molecular electronic memory circuit, fabricated at a density of 10(11) bits cm(-2) (pitch 33 nm; memory cell size 0.0011 microm2), that is, roughly analogous to the dimensions of a DRAM circuit projected to be available by 2020. A monolayer of bistable, [2]rotaxane molecules served as the data storage elements. Although the circuit has large numbers of defects, those defects could be readily identified through electronic testing and isolated using software coding. The working bits were then configured to form a fully functional random access memory circuit for storing and retrieving information.

Ultrahigh-Density Nanowire Lattices and Circuits

Abstract: We describe a general method for producing ultrahigh-density arrays of aligned metal and semiconductor nanowires and nanowire circuits. The technique is based on translating thin film growth thickness control into planar wire arrays. Nanowires were fabricated with diameters and pitches (center-to-center distances) as small as 8 nanometers and 16 nanometers, respectively. The nanowires have high aspect ratios (up to 106), and the process can be carried out multiple times to produce simple circuits of crossed nanowires with a nanowire junction density in excess of 1011 per square centimeter. The nanowires can also be used in nanomechanical devices; a high-frequency nanomechanical resonator is demonstrated.

Harnessing nanotopography and integrin–matrix interactions to influence stem cell fate

Abstract: Stem cells respond to nanoscale surface features, with changes in cell growth and differentiation mediated by alterations in cell adhesion. The interaction of nanotopographical features with integrin receptors in the cells' focal adhesions alters how the cells adhere to materials surfaces, and defines cell fate through changes in both cell biochemistry and cell morphology. In this Review, we discuss how cell adhesions interact with nanotopography, and we provide insight as to how materials scientists can exploit these interactions to direct stem cell fate and to understand how the behaviour of stem cells in their niche can be controlled. We expect knowledge gained from the study of cell-nanotopography interactions to accelerate the development of next-generation stem cell culture materials and implant interfaces, and to fuel discovery of stem cell therapeutics to support regenerative therapies.