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electron-beam-lithography
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Analysis of the Interaction of Electron Beam and External Field by Considering Space Charge Effect and its Application in EBL Nanolithography
, M.Sc. Thesis Sharif University of Technology ; Rashidian, Bizhan (Supervisor) ; Mehrani, Khashayar (Co-Advisor)
Abstract
Due to tremendous growth in usage of electron beams in different applications like VLSI, welding, chemical processes, Polymer industry and medical applications, precise study of these beams is of great importance. One of the most important parameters in studying electron beams characteristics is the phenomenon and effect of space charge. Although in most methods of analyzing electron optical systems, this effect is neglected, however in high density beams, this effect is bold. Space charge effect is due to interaction and electrostatic repulsion force between each of the electrons in the beam, which results in a change in shape and also divergence of beam. It is worth to mention that in...
Oxidation effects on transport characteristics of nanoscale MOS capacitors with an embedded layer of silicon nanocrystals obtained by low energy ion implantation
, Article Materials Science and Engineering B: Solid-State Materials for Advanced Technology ; Volume 124-125, Issue SUPPL , 2005 , Pages 494-498 ; 09215107 (ISSN) ; Shalchian, M ; Benassayag, G ; Coffin, H ; Bonafos, C ; Schamm, S ; Atarodi, S. M ; Claverie, A ; Sharif University of Technology
2005
Abstract
In this paper, we have studied the effect of annealing under slightly oxidizing ambient (N2 + O2) on the structural and electrical characteristics of a limited number of silicon nanoparticles embedded in an ultra-thin SiO2 layer. These nanoparticles were synthesized by ultra-low energy (1 keV) ion implantation and annealing. Material characterization techniques including transmission electron microscopy (TEM), Fresnel imaging and spatially resolved electron energy loss spectroscopy (EELS) have been used to evaluate the effects of oxidation on structural characteristics of nanocrystal layer. Electrical transport characteristics have been measured on less than one hundred nanoparticles by...
Shedding light on pseudocapacitive active edges of single-layer graphene nanoribbons as high-capacitance supercapacitors
, Article ACS Applied Energy Materials ; Volume 2, Issue 5 , 2019 , Pages 3665-3675 ; 25740962 (ISSN) ; Esfandiar, A ; Mehdipour, H ; Chaigneau, M ; Irajizad, A ; Moshfegh, A. Z ; Sharif University of Technology
American Chemical Society
2019
Abstract
In the field of energy storage by high-rate supercapacitors, there has been an upper limit for the total interfacial capacitance of carbon-based materials. This upper limit originates from both quantum and electric double-layer capacitances. Surpassing this limit has been the focus of intense research in this field. Here, we precisely investigate the effect of chemical functional groups and physical confinement on the electrochemical performance of graphene nanoribbons. We present the results of a quasi-one-dimensional single-layer graphene nanoribbon (120 nm in width and -100 μm in length) microelectrode fabricated by mechanical exfoliation of graphite, followed by electron beam lithography...
Effect of microstructure on rolling behavior of NiTi memory alloy
, Article Materials and Manufacturing Processes ; Volume 23, Issue 7 , 26 August , 2008 , Pages 646-650 ; 10426914 (ISSN) ; Badakhshan Raz, S ; Sharif University of Technology
2008
Abstract
NiTi shape memory alloy (SMA) ingots were produced by vacuum induction melting/casting unit. The effect of microstructure on the hot (1000C) and cold (room temperature) rolling workability of cast samples was investigated. Microstructure of the cast samples was related to the type of crucible which used for melting and the average vacuum pressure of VIM furnace. Optical microscope, scanning electron microscope (SEM), and energy dispersive technology (EDS) methods were used to inspect the origins of observed cracks after rolling processes. The results showed that the formation of both Ti4Ni2O and TiC impurities formed due to inappropriate melting conditions had detrimental effects on...
Visualising structural modification of patterned graphene nanoribbons using tip-enhanced Raman spectroscopy
, Article Chemical Communications ; Volume 57, Issue 56 , 2021 , Pages 6895-6898 ; 13597345 (ISSN) ; Esfandiar, A ; Lancry, O ; Shao, J ; Kumar, N ; Chaigneau, M ; Sharif University of Technology
Royal Society of Chemistry
2021
Abstract
Graphene nanoribbons (GNRs) fabricated using electron beam lithography are investigated using tip-enhanced Raman spectroscopy (TERS) with a spatial resolution of 5 nm under ambient conditions. High-resolution TERS imaging reveals a structurally modified 5-10 nm strip of disordered graphene at the edge of the GNRs. Furthermore, hyperspectral TERS imaging discovers the presence of nanoscale organic contaminants on the GNRs. These results pave the way for nanoscale chemical and structural characterisation of graphene-based devices using TERS. © The Royal Society of Chemistry 2021