InGaN(0001) surfaces prepared by molecular beam epitaxy have been studied using scanning tunneling microscopy and first-principles total energy calculations. Nanometer-size surface structures are observed consisting of either vacancy islands or ordered vacancy rows. The spontaneous formation of these structures is shown to be driven by significant strain in the surface layers and by the relativ...

The optical properties of ZnO nanowires containing defects are investigated using first-principles densityfunctional theory incorporating the LDA+U formalism. Calculations include defects in the form of substitutional N, Zn, and O vacancies as well as +1 charged O vacancy. Our calculations reveal that the presence of vacancies contribute strongly to optical absorption in the visible. Furthermor...

Point-defect-mediated diffusion processes are investigated in strained SiGe alloys using kinetic lattice Monte Carlo KLMC simulation technique. The KLMC simulator incorporates an augmented lattice domain and includes defect structures, atomistic hopping mechanisms, and the stress dependence of transition rates obtained from density functional theory calculation results. Vacancy-mediated interdi...

Using an optical tweezers apparatus, we demonstrate three-dimensional control of nanodiamonds in solution with simultaneous readout of ground-state electron-spin resonance (ESR) transitions in an ensemble of diamond nitrogen-vacancy color centers. Despite the motion and random orientation of nitrogen-vacancy centers suspended in the optical trap, we observe distinct peaks in the measured ESR sp...

We used the density functional theory and ab initio pseudopotentials to investigate He–H interaction in crystalline silicon. It was shown that both hydrogen and helium stimulate the formation of vacancy complexes. The presence of hydrogen decreases the vacancy and divacancy formation energies by about 2 eV. The presence of one or two helium atoms reduces the divacancy formation energy by 0.3 an...

Despite many years of experimental searches for a first-order Mott transition in crystalline-doped semiconductors, none have been found. Extensive experimental work has characterized a first-order metal-insulator transition in Li(x)CoO(2), the classic material for rechargeable Li batteries, with a metallic state for x < 0.75 and insulating for x > 0.95. Using density functional theory calculati...

although carbon nanotubes (cnt) have been employed as reinforcements in nanocomposites, presence of nano scale defects such as stone-wales and vacancy defects in carbon nanotubes (cnt) weakens the mechanical properties of these materials. in this paper the effects of defects in cnts on nanocomposite elastic behavior are investigated using molecular dynamics. stiffness matrices of cnt and nanoco...