Sharif Digital Repository

Thin films of materials, in order to have magnificent structure and properties, can use in complicated technology such as; electronic, optic and magnetic systems. Printed interconnects can be made by the deposition of suspensions of metal nanoparticles (e.g., silver and gold) followed by thermal sintering. The nanoparticle sintering process involves atomic diffusion resulting in shrinkage. As a result, the interconnects are prone to residual stresses generated during the thermal sintering process. The residual stress can cause cracks and delamination in the thin films and can cause permanent geometrical changes in the underlying substrates which may affect the functionality of the... 

An important issue in High-Frequency circuits is the transmission of electrical signals in Integrated Circuits and Printed Circuit Boards (PCBs). At high frequencies, however, the often used transmission lines suffer from high conductor and substrate loss as well as unwanted electromagnetic coupling to other circuit elements caused by parasitic substrate surface. One method through which both of the above problems may be solved is utilizing waveguide structures on PCBs and ICs. In this way, due to the reduction of conductor loss, a large proportion of signal passes easily. Moreover, and because of closed nature of cavity waveguides, neighboring circuits are protected against electromagnetic... 

The Cu2ZnSnS4 (CZTS) quaternary compound, with suitable optical and electrical properties, is one of the most interesting materials for absorber layer of thin film solar cell. Since all constituents of CZTS, are abundant in earth’s crust and non-toxic, it is a proper replacement for the materials like CdTe and CuInSe2. The CZTS pellet was synthesized by the solid-state reaction and deposited on soda lime glass substrates by pulsed laser deposition (PLD) method. PLD technique has the advantages of offering stoichiometric preservation during the materials transformation from target to substrate and good crystallinity due to the highly energetic species. CZTS has was deposited in order to... 

Graphene is a single-atomic two-dimensional crystal that has considerable properties due to its unique structure and physics with applications in different fields. Due to its atomic thin thickness, substrates have a considerable effect on the electrical properties of Graphene. As these effects are determinative of the general behavior of systems, one should consider this effect in the design and fabrication of a device. Moreover, the conventional fabrication methods for Graphene-based electronic devices restrict the possibility of the device fabrication on a wide range of substrates, specially flexible and biocompatible substrates.In this work, the LPCVD Graphene growth process has been... 

Hydroxyapatite (HA) is an attractive biomaterial due to its close chemical composition to bone and teeth. However, HA is brittle and has low strength under bearing loads, resulting in limition for orthopedic and dental applications. Two creative approaches have been developed to overcome this problem, using bioactive HA as coatings on metallic implants or as ceramic/metal composites. Carbon nanotubes (CNT) possess excellent mechanical properties to play the role as reinforcement for imparting strength and toughness to brittle hydroxyapatite (HA) bioceramic coating. Moreover, The addition of TiO2 to HA coatings has attracted considerable attention, since TiO2 is capable of increasing the...