The present work focuses on two types of quantum wire structures which were grown by molecular beam epitaxy (MBE). First, the sidewall quantum wires based on the selective growth on mesa stripe patterned GaAs(311)A are studied. Single stacked sidewall quantum wires with strong electronic coupling have been fabricated. p-i-n type LEDs of the quantum wires employing the amphoteric Si incorporatio...

Extensive experimental and theoretical investigations have made considerable progress toward understanding the nature of vibrational dynamics of amorphous silicon (a-Si). However, the changes in the vibrational spectrum of a-Si with external perturbations need to be explored. An investigation of a-Si under pressure is, therefore, important to understand not only changes in the vibrational spect...

In this thesis work, we have explored the possibility and the limitations of using atomistic simulation in studying structure and properties of carbon/ carbon interfaces and its integration with appropriate experimental techniques. In doing so, we have tested several interatomic potential functions for carbon and concluded that the potential functions tested are not ideally suited for all appli...

– We study in detail by means of ab-initio pseudopotential calculations the electronic structure of five-fold coordinated (T5) defects in a-Si and a-Si:H, also during their formation and their evolution upon hydrogenation. The atom-projected densities of states (DOS) and an accurate analysis of the valence charge distribution clearly indicate the fundamental contribution of T5 defects in origin...

Results of highly precise all-electron local spin density FLAPW calculations on (i) a close-packed 7-layer Ni (111) slab and (ii) a p (1 x 1) Ni monolayer on Cu (111) are presented. For Ni ( I l l ) , we find an enhancement of the magnetic moment for both the surface (to 0.63 pB) and sub-surface Ni layers (from a center layer value of 0.58 pB). In contrast, a slight decrease of the magnetic hyp...

It has long been understood that some of the key characteristics of materials, like grain boundaries, dislocation cores, and crack tips cannot be modeled realistically within the framework of continuum mechanics. It is believed that defects and surface effects play important roles at small scales, where the continuum assumptions are violated. Therefore, further information on a material at its ...

We report on scanning tunneling microscopy (STM) studies performed with single crystalline W[001] tips on a graphite(0001) surface. Results of distance-dependent STM experiments with sub-̊angström lateral resolution and density functional theory electronic structure calculations show how to controllably select one of the tip electron orbitals for highresolution STM imaging. This is confirmed by ...

BACKGROUND The tertiary system of nucleotide chain (NC) - gold nanoparticles (NPs) - carbon nanotube (CNT) represents a great interest in the modern research and application of the bio-nano-technologies. The application aspects include, for example, the development of electronic mobile diagnostic facilities, nanorobotic design for a drug delivery inside living cell, and so on. The small NC chai...

The strain energies in straight and bent single-wall carbon nanotubules (SWNTs) are calculated by taking account of the total energy of all the occupied band electrons. The obtained results are in good agreement with previous theoretical studies of different approaches and experimental observations. We calculate the Young’s moduli and wall thickness of SWNT from the bending strain energy for th...

The electronic and geometric structures of the clean a,nd Sb terminated Si(lOO)2x1 and Ge(lOO)-2x1 surfaaces have been investigated using a multi-technique approach. Low energy electron diffraction (LEED), scanning tunneling microscopy (STM), surface extended X-ray absorption fine structure (SEXAFS) spectroscopy and angle-integrated core-level photoemission electron spectroscopy (PES) were empl...