Sharif Digital Repository

In this thesis, we investigate some transport and many body properties of the 2DEG at the interface of LaAlO3=SrTiO3. First, following Boltzmann approach,we calculate conductivity and mobility of the system. We find that the mobility varies inversely with the cubic power of the carrier density ( / n3 2D) in good agreement with the experimental results. Taking in to account the variations of the dielectric constant of SrTiO3 with carrier density together with the variable impurity density are remarkably important in order to explain the abrupt decrease of the mobility with increasing the density in this system. We find that although the multiband nature of the system and interband... 

Molybdenum disulfide (MoS2) nanoflakes, a two-dimensional crystal with tunable bandgap depends on number of layers, is a promising candidate for future nanoelectronic devices. In the present research, flower shaped MoS2 nanoflakes have been synthesized via hydrothermal method. As part of the research, the growth of triangular MoS2 monolayer up to 10 micrometers has optimized by carring out several chemical vapor deposition experiments with varying deposition parameters. The prepared samples were characterized using optical, scanning electron, and atomic force microscopes, x-ray diffraction analysis, and Raman spectroscopy. Based on the experimental results, the growth mechanism has been... 

In this project, the ionization and dissociation of methane molecule by intense femto-second lasers has been studied. Dissociation probability is calculated for interacting CH4 molecule under Ti: Sapphire laser pulse with pulse durations of 10- 40fs in intensities at the range of 1014-1016 Wcm-2. Calculations are carried out with time-dependent density functional theory using Gaussian03 and Octopus packages as powerful computational chemical physics programs. Due to importance of the dependence of interaction dynamics to laser parameters, the effect of these parameters including different intensities, polarization, various pulse durations and pulse envelopes are investigated. The optimal... 

A global concern has arisen owing to rapid industrial development and population growth, resulting in energy scarcity and earth pollution. In this regard, developing green and sustainable methods for producing clean energy and solving environmental pollution problems have absorbed enormous attention. Among various auspicious strategies, semiconductor photocatalysis has been widely studied in recent years owing to its capabilities to obtain hydrogen as an energy carrier, to remove organic pollutants, and to reduce CO2 emission by converting solar energy into chemical energy. Recently, a metal-free semiconductor photocatalyst based on graphitic carbon nitride, g-C3N4, has received much...