The Nano-composite Nature of Vanadium Oxide Thin Films for Use in Infrared Microbolometers PDF Download

Author: Bryan Douglas Gauntt
Publisher:
ISBN:
Category :
Languages : en
Pages : 170

View

Book Description

Author: Michael Allen Motyka
Publisher:
ISBN:
Category :
Languages : en
Pages : 220

View

Book Description

Author: Kerry Elizabeth Wells
Publisher:
ISBN:
Category :
Languages : en
Pages :

View

Book Description

Author: Mengyang Zou
Publisher:
ISBN:
Category : Bolometer
Languages : en
Pages : 68

View

Book Description
Microbolometer IR imagers consist of an array of thermally sensitive pixels that change resistance as infrared radiation is focused onto the array. Commonly used thermoresisitive materials are amorphous silicon (a-Si) and vanadium oxide (VOx). Despite their use in image sensors, these films are extremely difficult to produce with widely varying process conditions being reported in the literature. Therefore, the goal of this work was to examine the process windows of some of these methods, including novel approaches such as oxygen ion assisted deposition (IAD), aluminum-induced crystallization and glancing angle deposition. Among the thermoresistive materials, vanadium oxide has been widely used in microbolometers due to their excellent thermoresistive properties, relatively fast thermal time constants and high temperature coefficient of resistance (TCR). In our work, we examined different physical vapor deposition methods including: RF reactive sputtering of metallic vanadium to produce vanadium oxide, thermal evaporation of vanadium films and subsequent oxidation, and Oxygen Ion-Assisted Deposition (IAD) of e-beam evaporated vanadium. In addition to VOx, amorphous silicon is also desirable because it can be easily integrated into the CMOS fabrication processes more than VOx. The hydrogenated amorphous silicon produced by PECVD has a high TCR and a relatively high optical absorption coefficient. In addition to PECVD, we used a glancing angle deposition and also examined a novel approach to create polycrystalline silicon from aluminum-induced crystallization.

Author: Hernan M. R.
Publisher:
ISBN:
Category : Science
Languages : en
Pages :

View

Book Description
This chapter describes a new deposition method proposed to achieve Vanadium Oxide VOx/V2O5 thin films with high temperature coefficient of resistance (TCR), intended to be used as functional material in IR microsensors (bolometers). The main aim of the work is to attain a deposition method compatible with the lift-off microstructuring technique in order to avoid the use of a reactive-ion etching (RIE) process step to selectively remove the VOx/V2O5 deposited layer in the course of the definition of the bolometer geometry, preventing the harmful effects linked to the spatial variability and the lack of selectivity of the RIE process. The proposed technique makes use of a two-stage process to produce the well-controlled VOx or V2O5 thin films by applying a suitable thermal annealing to a previously deposited layer, which was obtained before at room temperature by RF magnetron sputtering and patterned by lift-off. A set of measurements has been carried out with thin films attained in order to check the quality and properties of the materials achieved with this method. The results reached with V2O5 pure phase films are consistent with a charge transport model based on the small polarons hopping derived from Mott's model under the Schnakenberg form.

Author: Adem Ozcelik
Publisher:
ISBN:
Category :
Languages : en
Pages : 97

View

Book Description

Author: Paolo Mele
Publisher: Springer
ISBN: 9783319358642
Category : Technology & Engineering
Languages : en
Pages : 0

View

Book Description
This book provides a comprehensive overview of the science of nanostructured oxides. It details the fundamental techniques and methodologies involved in oxides thin film and bulk growth, characterization and device processing, as well as heterostructures. Both, experts in oxide nanostructures and experts in thin film heteroepitaxy, contribute the interactions described within this book.

Author: Afaf Almoabadi
Publisher:
ISBN:
Category :
Languages : en
Pages : 92

View

Book Description
ABSTRACT Electrochromic Properties of Vanadium Pentoxide Nanostructured Thin Films Afaf Almoabadi The focus of this work is the improvement of the electrochromic properties of vanadium pentoxide thin films in order to expand its use. Indeed, because of its rather poor electrochromic properties, until now, vanadium pentoxide has only been used as a storage material in an electrochromic device, in conjunction with tungsten oxide, molybdenum oxide etc. To this purpose, vanadium pentoxide thin films were prepared under different conditions and characterized by using optical and electrochemical methods. Films were deposited on indium tin oxide (ITO) substrates by dip-coating at both room- and sub-zero temperature (-100C) and porosity in the sol-gel prepared vanadium pentoxide film was created by using templating methods. The morphology, optical and electrochromic properties of the macro- and mesoporous films, prepared in the presence of structure-directing agents such as polystyrene microspheres and triblock copolymer, have been compared with those of dense films. By using various methods to remove the template material, it was shown that the morphology of the vanadium pentoxide film can be controlled and new nanostructures can be created. The transformation of the lamellar into a nanorod structure, observed when the film is heated at 425-500◦C for several hours, resulted in the development of an elegant method for the synthesis of vanadium oxide nanostructures. The electrochromic performance of the nanorods prepared through the thermal treatment was found to be superior to that of the vanadium pentoxide with the layered structure, especially in the near-infrared region, demonstrating their potential for electrochromic applications. The structure, morphology, optical and electrochromic properties of dense and porous vanadium oxide films, coated at low temperature were also determined and compared to those of the corresponding films, deposited under room-temperature conditions. The results indicated that in the films coated at -100C, a residual compressive stress exists that originates from a non-uniformity in depth of the film, most probably, due to the formation of micro voids during the deposition. The micro voids are preserved during the heat-treatment of the films. The "micro void" morphology was found to account for the considerably improved electrochromic properties of the sub-zero dip-coated films. Low-temperature coated films, heated at 4500C for several hours, undergo the transformation from a layered to a highly uniform nanorod structure with important potential optoelectronic applications. The overall aim of this work is thus to evaluate how the morphology of vanadium pentoxide thin films is instrumental in obtaining a material with a high lithium ion intercalation capacity. With an appropriate morphology, the performance of vanadium oxide as electrochromic material and as cathode in lithium ion batteries can be improved significantly. For this purpose, both layered (dense and porous) and nanorod films were prepared and characterized. Scanning electron microscopy, cyclic voltammetry and electrical impedance spectroscopy measurements were used for the characterization of the different V2O5 films.

Author: J. A. Tenreiro Machado
Publisher: Springer Nature
ISBN: 9811641692
Category : Mathematics
Languages : en
Pages : 191

View

Book Description
This book explores recent developments in theoretical research and mathematical modelling of real-world complex systems, organized in four parts. The first part of the book is devoted to the mathematical tools for the design and analysis in engineering and social science study cases. We discuss the periodic evolutions in nonlinear chemical processes, vibro-compact systems and their behaviour, different types of metal–semiconductor self-assembled samples, made of silver nanowires and zinc oxide nanorods. The second part of the book is devoted to mathematical description and modelling of the critical events, climate change and robust emergency scales. In three chapters, we consider a climate-economy model with endogenous carbon intensity and the behaviour of Tehran Stock Exchange market under international sanctions. The third part of the book is devoted to fractional dynamic and fractional control problems. We discuss the novel operational matrix technique for variable-order fractional optimal control problems, the nonlinear variable-order time fractional convection–diffusion equation with generalized polynomials The fourth part of the book concerns solvability and inverse problems in differential and integro-differential equations. The book facilitates a better understanding of the mechanisms and phenomena in nonlinear dynamics and develops the corresponding mathematical theory to apply nonlinear design to practical engineering. It can be read by mathematicians, physicists, complex systems scientists, IT specialists, civil engineers, data scientists and urban planners.

Author: Hiroyuki Fujiwara
Publisher: John Wiley & Sons
ISBN: 9780470060186
Category : Technology & Engineering
Languages : en
Pages : 388

View

Book Description
Ellipsometry is a powerful tool used for the characterization of thin films and multi-layer semiconductor structures. This book deals with fundamental principles and applications of spectroscopic ellipsometry (SE). Beginning with an overview of SE technologies the text moves on to focus on the data analysis of results obtained from SE, Fundamental data analyses, principles and physical backgrounds and the various materials used in different fields from LSI industry to biotechnology are described. The final chapter describes the latest developments of real-time monitoring and process control which have attracted significant attention in various scientific and industrial fields.