Fabrication of thin film solar cell materials by APCVD

Thin film solar cells are currently being implemented commercially as they reduce the amount of semiconductor material required for each cell when compared to silicon wafers, thereby lowering the cost of production. Currently two direct band gap chalcogenide thin-film technologies, CdTe and CuInGa(S,Se)2 (CIGS), yield the highest reported power conversion efficiencies of 16.5% and 20.3%, respectively. In addition, Cu2ZnSnS4 (CZTS) is one of the most promising chalcogenide thin film photovoltaic absorber materials; with an optimal band gap of about 1.5 eV. More importantly, CZTS consists of abundant and non-toxic elements, so research on CZTS thin-film solar cells has been increasing significantly in recent years. Moreover, Sb2S3 based chalcogenide thin films have been proposed for use in photovoltaic applications. The preparation of chalcogenide thin films solar cells commonly use physical vapour deposition methods including thermal/e-beam evaporation, sputtering, and pulsed laser deposition, electrochemical deposition, spray pyrolysis, solution-based synthesis, followed by the sulfurization or selenization annealing process. In this paper, we report a non-vacuum process, using atmospheric pressure chemical vapour deposition (APCVD), to fabricate chalcogenide thin film solar cell materials as well as transparent conductive oxide (TCO) thin films. The optical, electrical, and structural properties of these materials were characterized by UV-VIS-NIR, four-point probes, SEM, EDX, XRD, Micro-Raman

Thermally stable low current consuming gallium and germanium chalcogenides for consumer and automotive memory applications

The phase change technology behind rewritable optical disks and the latest generation of electronic memories has provided clear commercial and technological advances for the field of data storage, by virtue of the many well known attributes, in particular scaling, cycling endurance and speed, that chalcogenide materials offer. While the switching power and current consumption of established germanium antimony telluride based memory cells are a major factor in chip design in real world applications, often the thermal stability of the device can be a major obstacle in the path to the full commercialisation. In this work we describe our research in material discovery and characterization for the purpose of identifying more thermally stable chalcogenides for applications in PCRAM

Chalcogenide metamaterial phase change all-optical switch of nanoscale thickness

Non-volatile, bi-directional, all-optical switching in a phase-change metamaterial delivers high-contrast transmission and reflection modulation at visible and infrared wavelengths in device structures only ~ λ/8 thick

All-dielectric free-electron-driven holographic light sources

It has recently been shown that holographically nanostructured surfaces can be employed to control the wavefront of (predominantly plasmonic) optical-frequency light emission generated by the injection of medium-energy electrons into a gold surface. Here we apply the concept to manipulation of the spatial distribution of transition radiation emission from high-refractive-index dielectric/semiconductor target materials, finding that concomitant incoherent luminescent emission at the same wavelength is unperturbed by holographic surface-relief structures, and thereby deriving a means of discriminating between the two emission components.Comment: 5 pages, 3 figure

Shape memory plasmonic metamaterials

We demonstrate the first shape-memory-alloy-based reconfigurable metamaterial. The structural elements of such metamaterials deform with hysteresis in response to heating and cooling, resulting in non-volatile switching of the shape memory metamaterial’s optical properties

Metamaterial electro-optic switch of nanoscale thickness

We demonstrate an innovative concept for nanoscale electro-optic switching. It exploits the frequency shift of a narrow-band Fano resonance mode in a plasmonic planar metamaterial induced by a change in the dielectric properties of an adjacent chalcogenide glass layer. An electrically stimulated transition between amorphous and crystalline forms of the glass brings about a 150 nm shift in the near-infrared resonance providing transmission modulation with a contrast ratio of 4:1 in a device of subwavelength thickness

Lithography assisted fiber-drawing nanomanufacturing

We present a high-throughput and scalable technique for the production of metal nanowires embedded in glass fibres by taking advantage of thin film properties and patterning techniques commonly used in planar microfabrication. This hybrid process enables the fabrication of single nanowires and nanowire arrays encased in a preform material within a single fibre draw, providing an alternative to costly and time-consuming iterative fibre drawing. This method allows the combination of materials with different thermal properties to create functional optoelectronic nanostructures. As a proof of principle of the potential of this technique, centimetre long gold nanowires (bulk Tm = 1064°C) embedded in silicate glass fibres (Tg = 567°C) were drawn in a single step with high aspect ratios (>104); such nanowires can be released from the glass matrix and show relatively high electrical conductivity. Overall, this fabrication method could enable mass manufacturing of metallic nanowires for plasmonics and nonlinear optics applications, as well as the integration of functional multimaterial structures for completely fiberised optoelectronic devices