Mid-wavelength infrared type-II InAs/GaSb superlattice for photodetectors

Type-II superlattices (T2SLs) have emerged as a promising technology for infrared detectors compared to the state-of-art mercury cadmium telluride (MCT). T2SLs have shown great potential for mid-wavelength infrared (MWIR) detectors but have yet to attain their theoretically predicted performance. Simulation, fabrication, and characterisation were utilised in this research project to improve the performance levels of MWIR T2SL detectors. Using the molecular beam epitaxy (MBE) reactor, different interfacial growth schemes were used to accommodate internal strain caused by the lattice mismatches in T2SL. The project involves band heterostructure simulations, growth schemes, structural and optical characterisations, and electrical characterisation of fabricated T2SL p-i-n diode. Reference T2SL samples were evaluated by X-ray diffraction (X-RD), atomic force microscopy (AFM), and transmission electron microscopy (TEM). An 8-band k·p approach for band heterostructure simulation explains PL experimental findings. Photoluminescence (PL) measurements probe the band structure and bandgap energy information. T2SL p-i-n diodes fabrication process was optimised using standard photolithography. The diode electrical performance of the T2SLs was examined by current-voltage (I-V) measurements using a cryogenic probe station. Investigation of structural and optical properties of the grown T2SL samples with interfacial growth schemes, namely incorporating an InSb compensation interface (IF) layer, was carried out to improve the material quality. AFM and TEM measurements revealed structural degradation due to the additional strain and lattice mismatch introduced by the InSb IF layers. However, including the InSb IF layer has improved the optical property of the T2SL. Band heterostructure simulation was performed to understand the possibility of atomic intermixing and segregation at the T2SL interfaces. Fabrication processes of T2SL single-pixel diodes were performed by wet etch, dry etch, and a combination of both approaches. The I-V characteristics revealed that the current density of the wet-etched devices is improved by approximately four orders of magnitude at low temperatures in comparison with the dry-etched devices, but they are comparable at high operating temperatures (HOT). Lastly, developments of wet etching processes were investigated using inorganic solutions, such as hydrochloric and phosphoric acids and organic solutions, including citric acid

Fundamentals and Recent Advances in Epitaxial Graphene on SiC

This book is a compilation of recent studies by recognized experts in the field of epitaxial graphene working towards a deep comprehension of growth mechanisms, property engineering, and device processing. The results of investigations published within this book develop cumulative knowledge on matters related to device-quality epaxial graphene on SiC, bringing this material closer to realistic applications

Wide Bandgap Based Devices: Design, Fabrication and Applications, Volume II

Wide bandgap (WBG) semiconductors are becoming a key enabling technology for several strategic fields, including power electronics, illumination, and sensors. This reprint collects the 23 papers covering the full spectrum of the above applications and providing contributions from the on-going research at different levels, from materials to devices and from circuits to systems

Properties and Applications of Graphene and Its Derivatives

Graphene is a two-dimensional, one-atom-thick material made entirely of carbon atoms, arranged in a honeycomb lattice. Because of its distinctive mechanical (e.g., high strength and flexibility) and electronic (great electrical and thermal conductivities) properties, graphene is an ideal candidate in myriad applications. Thus, it has just begun to be engineered in electronics, photonics, biomedicine, and polymer-based composites, to name a few. The broad family of graphene nanomaterials (including graphene nanoplatelets, graphene oxide, graphene quantum dots, and many more) go beyond and aim higher than mere single-layer (‘pristine’) graphene, and thus, their potential has sparked the current Special Issue. In it, 18 contributions (comprising 14 research articles and 4 reviews) have portrayed probably the most interesting lines as regards future and tangible uses of graphene derivatives. Ultimately, understanding the properties of the graphene family of nanomaterials is crucial for developing advanced applications to solve important challenges in critical areas such as energy and health

ICR ANNUAL REPORT 2020 (Volume 27)[All Pages]

This Annual Report covers from 1 January to 31 December 202

Solution Synthesized Nanostructured Thermoelectric Materials

Thermoelectric heat engines are currently used in several niche applications for electricity generation and cooling. Many additional applications would be practical if thermoelectric materials with improved figures of merit could be made. Over the past twenty years, many nanostructured materials have been shown to possess improved figures of merit compared to their bulk counterparts mostly due to the reduction in thermal conductivity associated with nanostructured materials. Several classes of solution synthesized nanostructured materials have achieved high figures of merit, yet significant room for improvement exists for solution synthesized nanostructured PbTe

Towards Oxide Electronics:a Roadmap

At the end of a rush lasting over half a century, in which CMOS technology has been experiencing a constant and breathtaking increase of device speed and density, Moore's law is approaching the insurmountable barrier given by the ultimate atomic nature of matter. A major challenge for 21st century scientists is finding novel strategies, concepts and materials for replacing silicon-based CMOS semiconductor technologies and guaranteeing a continued and steady technological progress in next decades. Among the materials classes candidate to contribute to this momentous challenge, oxide films and heterostructures are a particularly appealing hunting ground. The vastity, intended in pure chemical terms, of this class of compounds, the complexity of their correlated behaviour, and the wealth of functional properties they display, has already made these systems the subject of choice, worldwide, of a strongly networked, dynamic and interdisciplinary research community. Oxide science and technology has been the target of a wide four-year project, named Towards Oxide-Based Electronics (TO-BE), that has been recently running in Europe and has involved as participants several hundred scientists from 29 EU countries. In this review and perspective paper, published as a final deliverable of the TO-BE Action, the opportunities of oxides as future electronic materials for Information and Communication Technologies ICT and Energy are discussed. The paper is organized as a set of contributions, all selected and ordered as individual building blocks of a wider general scheme. After a brief preface by the editors and an introductory contribution, two sections follow. The first is mainly devoted to providing a perspective on the latest theoretical and experimental methods that are employed to investigate oxides and to produce oxide-based films, heterostructures and devices. In the second, all contributions are dedicated to different specific fields of applications of oxide thin films and heterostructures, in sectors as data storage and computing, optics and plasmonics, magnonics, energy conversion and harvesting, and power electronics

Superconductor

This book contains a collection of works intended to study theoretical and experimental aspects of superconductivity. Here you will find interesting reports on low-Tc superconductors (materials with Tc 30 K). Certainly this book will be useful to encourage further experimental and theoretical researches in superconducting materials