Sharif Digital Repository

The need for better characterization systems (electron microscopes) and high resolution lithography systems, have made electron beams systems an interesting choice for research and development. In fact, all of the above applications require ideal electron beams (beams with minimum energy spread, maximum current density, and minimum spotsize), and electron-optic lenses (simple lenses with minimum aberration). In this research, theoretical aspects of electron emission and lens systems are reviewed. Field emission array (FEA) electron guns are introduced as electron sources with minimum energy spread, and a new simulation method is presented in order to minimize the complexity, and reduce the... 

The fabrication of future electronic and optical devices will require advanced nanofabrication techniques that realize high spatial resolution and high precision in controlling size and position, and that are applicable to various materials. Near-field CVD (NF-CVD) was proposed to solve these problems with no need to perform nanolithography prcesses. NFCVD system has two major subsystems, first vacuum chamber and gas distribution system for delivering parent gases to the chamber and second, a nanopositiong system to keep the probe and the sample in the constant systems.In this dissertation we have set up a piezoelectric nanopositiong system and its driver modules. The positioning accuracy... 

An inconsistency between the circular symmetric geometry of conventional optical imagers and the geometry of long linear sensors used in today line scan cameras, results in suboptimal separate design of optics and electronics of scanner systems. In this thesis two new imaging methods namely Foveated scanning (FS) and Linear Fovea (LF) are proposed to tackle this problem and to design lenses that are better matched to linear sensors. Both techniques are based on the known Foveated Imaging (FI) scheme and are employed to enlarge the one dimensional resolved field of view (RFOV) of conventional lenses and to permit prioritized performance on a Line-of-Interest (LOI) in the image plane where the... 

Today, in order to reach atomic scale resolution, novel nanolithography methods, known as unconventional nanolithography, have been presented, since conventional methods, including photolithography and scanning beam lithography are fundamentally unable to fulfill this need. In this work, a specific type of unconventional lithography, known as scanning probe lithography, is presented. Scanning probe lithography takes advantage of the interactions between a very sharp probe and the sample in nanoscale distances to control this distance, and hence enable the modification of the sample using this sharp probe. In mechanical scanning probe lithography, the probe is used mechanically to change the... 

Despite ongoing progress in the field of nanophotonics, characterizing and identifying optical interactions in the deep subwavelength dimensions have remained challenging. The inability of conventional optical microscopy in nanoscale imaging, due to diffraction limit, was the main stimulus for research on new characterizing methods with the capability of non-destructive high-resolution imaging in which the sample preparation is not required. To achieve this goal, scanning probe microscopes are introduced to extract valuable high spatial harmonics from near field measurements on the sample. In this thesis, by focusing on the probe-sample interaction, the near field behavior of the plasmonic... 

Plasma is a quasi-neutral gas consist of charged and neutral particles that manifest collective behavior. Plasma is an ionized gas in which all or a significant portion of its atoms have lost one or more electrons and become a set of positive ions and electrons. Plasma is one of the four primary states of matter. This project intends to generate plasma by a pulsed electric discharge in a gaseous environment. At first, in this project, the proper excitation circuits are collected and compared, then based on the feasibility of production, applicable methods are selected and constructed. The construction steps were such that the selected circuits were first simulated with the appropriate... 

Very dangerous gases are used in ion implanter machines. Opening and closing the valves of these gases can be very dangerous. In this project, these valves are inspected, monitored and opened and closed from a safe distance. To do this, we must monitor and control the above system by using the latest and most efficient technologies available and with the least delay. For accurate and precise monitoring, clear images should be obtained from the location and changes should be detected, and the device can be controlled very quickly with the necessary commands. To do this, one must have an accurate and comprehensive knowledge of processors and communication protocols, and also pay attention to... 

plasma characterization has become an essential tool for characterization of etching process in fabrication of nano-electronic devices. The existing methods, such as Langmuir probe and interferometry, have shown drawbacks including disturbing the plasma and sensitivity to mechanical and thermal stability of the measuring systems. In recent years, due to the scale down of microelectronic devices and increase of their sensitivity to disturbance in the plasma etching process, a demand for measuring methods offering less disturbance has arisen. Plasmonic structures, owing to their unprecedented field enhancement and confinement, have been extensively studied. Their sub-wavelength dimensions,... 

Ion sources have changed significantly since ion implantation was first used commercially. High beam current and good performance with long lifetime are the keys in an ion source. Freeman ion sources are facing challenges such as the short lifetime of the filament, the single charge of the extracted ions. In the third chapter, these challenges and solutions for them are described. In this thesis, while examining different types of ion sources and comparing them with the combination and simulation of Freeman Varian 300XP ion source performance, an improved Freeman ion source is also presented. Also, the results obtained through simulation using Comsol 6.1 software and MATLAB program have been... 

Businesses are dependent on mining of their Big Data more than ever and configuring clusters and frameworks to reach the best performance is still one of the challenges. An accurate performance prediction of the Big Data application helps reduce costs and SLA-violations with better tuning of the configuration parameters. Among the Big Data frameworks, Hadoop, Tez, and Apache Spark are the widely used and popular ones, with the MapReduce and graph-based workflows, usually running on top of the YARN cluster. While a great number of attempts have been made to predict the execution time of Big Data applications, to the best of our knowledge, none of them considered multiple simultaneous YARN... 

Carbon nanotubes, due to their extraordinary electronic and physical properties, have attracted much attention in the last decade. Some of their potential applications are in CNT-field effect transistor, field emission devices, physical and chemical sensors, micro and Nanoelectromechanical systems and Nano antenna. In this thesis, we have first reviewed some features of carbon nanotubes and the advantages of PECVD method compared with thermal CVD. In the second part the role of some of the materials (such as H2/NH3/C2H4) in CNT growth are studied. We created a square pattern on the silicon wafer by photolithography. Afterwards, titanium and nickel deposition is done on the mentioned pattern.... 

The purpose of this thesis is construction of a characterization system, for plasmonic nanoparticles. plasmonic nanoparticles are metallic particles in nanometer scale, which can confine the electromagnetic field, in their induced electric dipole, in a wide range of frequency. This optical property lead to many applications such as, medicine cancer therapy, controlled releasing of drugs, solar cells and interconnections in integrated photonic circuits.Since, optical properties are the most important properties of plasmonic nanoparticles, we need a system to characterize them optically. There are different ways of optical characterization, which need a common tools, including light sources,... 

For realization of nanosale photonic device required by the future system, electron beams, and scanning probe microscopes have been used to control the site on the subtrate. However, these techniques have a fatal disadvantage because they cannot deal with insulators and Diffraction of light, limiting their application.To overcome this difficulties, we design and implement near-field optical chemical vapor deposition, which enables the fabrication of nanometer-scale structure, while controlling their position. To guarantee that an optical near field is generated sufficiently, we fabricated a sharped W-tip by electrochemical etching. The separation between the W-tip and the substrate was kept... 

Nowadays, thin film alloy deposition has much importance. These alloys are used for various opto-electronic device applications such as liquid crystal displays, flat panel displays, plasma displays, solar cells and computer memories. Exact control of elements ratio in alloy is one of the important issues in deposition of thin film alloys. In alloy deposition with electron beam gun method from its elements, uniformity improvement of each layer is a way to maintain elements ratio in different parts of sample. This uniformity has much importance especially in optical coatings such as high quality antireflection coatings, highly selective filters and low loss reflectance coatings. In this... 

With the increasing development of the semiconductor industry, the density integration of integrated circuits with affordable expenses has gained a special place between different researches. Nanolithography as a way to decrease the size of patterns has a significant contribution in integration of circuits. Scanning Probe Nanolithography (SPNL) is one of the most important nanolithography methods due to its ability to create patterns with an extremely high resolution and direct patterning. Scanning Near-field Optical Lithography (SNOL) has the advantages of the usage of optic such as non-direct effect on sample and the advantages of scanning systems such as high resolution. In first part of...