Sharif Digital Repository

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... 

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 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... 

In this thesis, the effect of radiation created in processes such as ion implantation and plasma on different types of semiconductor devices has been investigated. In the first part, after presenting the basic concepts, the basics of the interaction of energetic particles with semiconductor devices and elements used in integrated circuits have been discussed, and the damage threshold in each type of these devices has been summarized, then in the second part, according to Due to the necessity of revealing energetic particles, the methods of doing this work have been compared with each other from the point of view of engineering. In the third and fourth sections, after presenting the Monte... 

The main objective of this thesis is to investigate the scaling laws of electrical breakdown and the devices that use it as the main current-passage mechanism. To achieve this goal, first, the physical phenomena involved in electrical breakdown and the mechanisms that cause electrical breakdown in different environments have been investigated. It is determined which phenomena become more important with down scaling and which phenomena lose their importance, and how the electrical breakdown mechanism changes based on the importance of these phenomena. In the second step, spark gap switches that use electrical breakdown as the main current-passage mechanism have been introduced, and dependence... 

In the fabrication of semiconductor devices, uniformity of thin films has many important influences on optical and electrical properties of the device. many attempts have been done on the enhancement of the uniformity of thin films so far. In this thesis, first the effect of angular variation of source with respect to the target on uniformity in the evaporation coating system has been studied, then an in situ positioning system for substrate has been designed and fabricated. After finding the thickness’s profile for Ag and Cu in Electron Beam Gun system, we studied the motion pattern of the target for improving the uniformity. This positioning system can be used to any coating systems. in... 

Nowadays electron beams have extensive applications in electon-optic devices such as microwave devices, electron microscopes and flat displays. So shaping and confinment of electron beams is of great importance. In the other hand, scaling of electron emitters to atomic limit causes new chalanges in reliability and beam shaping. Designing electron optic devices for nanoscale emitters needs great knowledge regarding materials properties and electron optic systems behavior in nano scale. In this study, beside providing basic optics of electron beam and effects Of external electronmagnetic fields, properties of electron optical devices
Considering nano scale limitations is considered. In... 

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... 

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... 

X-ray radiation is an ionizing radiation that can be produced under some conditions in an ion implanter and can have significant effects on equipment and personnel health. In this dissertation, we first examine the properties of ionizing radiations and their effects of electronic devices and discuss the general properties of common detectors. Next, Using Silvaco TCAD and GEANT4 we will simulate the interaction of ionzing radiation with energies up to 300 keV with electronic devices including a commercial off the shelf photo diode and a specialized x-ray detector and show that these devices can efficiently reveal informations of a radiation source to the user. Also, it has been shown that... 

The process of vein is a simple yet important process. This process may, in some cases, have problems that can cause the patient to be harmed as well as in some cases.In this project, we were able to imagine the veins by designing and manufacturing a device with a near -infrared wave and a handle of Razbari Pie and the anatomy of the hand, as well as processing this image and becoming a suitable image for nurses. do . First, the image of the veins was captured by infrared LEDs with infrared LEDs with an infrared camera and then processed by the Python Camera Picture program, which is based on anatomy -based process using morphological operations. And we've displayed. The video is taken and... 

Because of widespread use of optical communication systems, analysis of optical wavepacket behavior during propagation in optical devices is of great importance. On the other hand, constant demand for improving the quality of data transmission and increasing data processing speed raises the necessity of studying novel electromagnetic structures for the purpose of designing new optical devices. Therefore, Photonic Crystal (PC) based structures, for their unique optical properties, have been subject of vast investigation in last two decades. Control of optical wavepacket behavior in photonic crystal based structures is considered in the present dissertation. Depending on the structure under... 

At Lake Urmia (LU) greatest extent, it was the largest lake in the Middle East and the sixth-largest saltwater lake on Earth, with a surface area of approximately 5,200 km2. The lake has shrunk to 10% of its former size due to damming of the rivers that flow into it, and the pumping of groundwater from the surrounding area. Moreover, as the lake shriks its potentional to be a major dust sources increases. A Hybrid Single-Particle Lagrangian Integrated Trajectory (HYSPLIT) model was used to investigate and track the extent of dust emission and aerosol concentration over Lake Urmia marginal dust spots in order to identify the affected and critical areas. Also, percent movement, propagation... 

Drilling Operations constitute more than fifty percent of total costs of well construction operations. Due to this fact, optimization of drilling operations could have significant effect on decrease in total costs of well construction. It is mentioning worthy that there are a variety of parameters which affect drilling operations from the view point of optimization. In many cases several of those aforementioned parameters are contrary in nature. Thus obtaining an integrated approach to optimize the operation by considering these effects is necessity. The goal of this thesis is to investigate different influential parameters of drilling operation optimization and to develop computer-based... 

Alkali-activated fly ash-slag (AAFS) is a new type of sustainable construction material widely studied in recent years for its desirable mechanical properties and low environmental impacts. In this study, the effects of the slag incorporation from 10 to 30% of fly ash are investigated on the strength, pore structure, and transport properties of the AAFS with various levels of fly ash replacements with slag. The unconfined compression and ultrasonic pulse velocity tests were performed to evaluate the mechanical properties of the AAFS concrete. Microstructural and mineralogical changes were studied by porosity, N2-adsorption/desorption, and SEM/EDX tests. Additionally, transport properties...