Sharif Digital Repository

Considering the importance of biocompatibility of implantable prothesis’, metallic alloys have weaker corrosion resistance than ceramics. In order to extend usage of nanomaterials to improve the bio-properties of materials, Nano-structured ceramic coatings are being suggested to improve corrosion resistance and biocompatibility of prosthesis. Meanwhile, very good properties of TiN, such as corrosion resistance and mechanical properties as a thin film coating are undeniable. In this study, TiN and Ti2N thin film were deposited on Ti-based substrate, using PVD and Magnetron sputtering at different argon to nitrogen ratio. The crystal structure of the films was examined using Grazing XRD... 

Porous thin films have becom very atractive due to their applications in many types of electronic and optical devices. There are several methods for deposition of such films. Chemical method for deposition of nanoporous thin films are relatively simple, but usually hard to control. In this thesis, chemical deposition of thin porous Molybden films is reported. In addition, an available sputtering system has been modified and, controlled porosity thin films were then deposited on glass and silicon substrates using GLAD method.These films have been characerized, and compared with chemically deposited porous thin films  

Analog SQUIDs have limited slew rate and dynamic range and these problems make it hard to operate SQUID systems in unshielded applications like Bio-magnetic imaging and NDE. Recently by combining analog SQUIDs and RSFQ Logic, new class of magnetic sensors are introduced. These sensors have an acceptable sensitivity and very high dynamic range. On the other hand these sensors, Which are called Digital SQUIDs, can be directly connected to digital signal processing stages. In This work, for first time, a digital SQUID completely based on i-directional RSFQ was designed and optimized. using Bi-directional RSFQ, one can significantly simplify the digital SQUID circuit design and therefore... 

In this study, transparent conductive thin film of Aluminum doped ZnO (ZnO:Al) have been fabricated thorough RF sputtering. The main goal of fabrication of these layers is achieving thin films with minimum resistivity and maximum optical transparency in visible range of spectrum employing as transparent electrodes and buffer layer at the entirely oxidized solar cells. To achieve the suitable structure, various parameters including pressure, power and the thickness of the deposition and annealing on morphologies of thin film has been investigated. According to these results, thin film of ZnO:Al has the transparency of 80% in the visible light range . Doping of ZnO with Aluminum caused... 

Recently nanostructure materials have used in various technologies and hence an extensive part of research focused on preparing and optimization of growth of nanostructure materials. Usually common procedure is based on a two-step process. First, construction a pre-layer by means of different deposition methods and then formation a nanostructure with a thermal treatment which increases the cost of research. Hence with one step method such as glancing angle deposition (GLAD ( it is possible to form a desirable structure with low cost. In this research Nano columns of tungsten was deposited on Si(133) by means of GLAD-RF sputtering without any heat treatment at substrate rotational speed ( )... 

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.... 

Design and construction process of special kind of sputter ion pump is described briefly in this paper. In order to investigate the optimization of effective parameters in choosing and designing ILSF ion pumps, this pump has been designed and manufactured. By optimizing some parameters such as dimension and shape of penning cells, anode voltage, magnetic field and internal structure of pump, it is possible to significantly decrease the cost of construction and operation of synchrotron vacuum system. By using the results of simulations and calculations of electromagnetic field, plasma simulation or glow discharge, titanium sputtering, etc., critical parameters in design of internal structure... 

Transparent conductive materials have been widely used in semiconductor technology. Among them all, Indium tin oxide (ITO) has been utilized as electrodes in liquid crystal displays, solar cells, heat reflecting films and gas sensors.In general, the desired properties of transparent conductive oxides are high conductance and transmission. However, due to the complexity of ITO molecular structure, the film properties strongly depend on the depositon parameters.In first part of this thesis, physical properties and electrical characteristic of ITO films, different deposition techniques, and effects of deposition parameters (substrate temperature, pressure, power, etc. ) on film properties are... 

Recently, nickel oxide nanostructures with NaCl-type structure have a variety of applications due to excellent chemical stability, as well as optical, electrical and magnetic properties. In this research, first by using DC and RF sputtering methods,nickel thin films were deposited on Si (100) and glass lame substrates under different experimental conditions (Discharge power, pressure and growth time).The deposited layers were annealed in air at different temperatures to obtain and compare their crystalline structures. Nickel oxide nanostructures grown on the Si (100) were studied by scanning electron microscopy analysis (SEM) to determines surface morphology, atomic force microscopy (AFM)...