Defect engineering has brought about a unique level of control for Si-based semiconductors, leading to the optimization of various opto-electronic properties and devices. With regard to perovskite transition metal oxides, O vacancies have been a key ingredient in defect engineering, as they play a central role in determining the crystal field and consequent electronic structure, leading to impo...

Measurements of conductivity and thermopower as a function of oxygen fugacity (fO2) are used to derive a model for conduction in olivine. Thermopower at 1000– 1200◦C is between 50 and 400 μV/K and has a positive fO2 dependence, and electrical conductivity exhibits approximately a /11 power dependence on fO2 . However, small polarons, considered to be the conducting defect in olivine at these te...

With the first-principle method, we studied effects of type and position defects on defect formation energy, electronic band structure, electron mobility 4-layer hexagonal system silicon carbon (4H–SiC). The vacancy energy is smaller than interstitial energy. C smallest, while Si largest. little affected by position. structure shows semi-metallic property due to defect, it a bandgap antisite de...

Tungsten (W) is considered to be the most promising plasma-facing material in fusion reactors. During their service, severe irradiation conditions create plenty of point defects W, which can significantly degrade performance. In this work, we first employ molecular static simulations investigate interaction between a 1/2[111] dislocation loop and vacancy-type defect including vacancy, di-vacanc...

Vacancies in graphene present sites of altered chemical reactivity and open possibilities to tune graphene properties by defect engineering. The understanding of chemical reactivity of such defects is essential for successful implementation of carbon materials in advanced technologies. We report the results of a systematic DFT study of atomic adsorption on graphene with a single vacancy for the...

The density of oxygen vacancies in semiconductor gas sensors was often assumed to be identical throughout the grain in the numerical discussion of the gas-sensing mechanism of the devices. In contrast, the actual devices had grains with inhomogeneous distribution of oxygen vacancy under non-ideal conditions. This conflict between reality and discussion drove us to study the formation and migrat...

Vacancy-mediated climb models cannot account for the fast, direct coalescence of dislocation loops seen experimentally. An alternative mechanism, self climb, allows prismatic dislocation loops to move away from their glide surface via pipe diffusion around the loop perimeter, independent of any vacancy atmosphere. Despite the known importance of self climb, theoretical models require a typicall...

Native defects in cuprous oxide Cu2O are investigated by using first-principles calculations based on density-functional theory. Considering the formation of copper and oxygen vacancies, antisites and interstitials, and a copper split-vacancy complex defect, we analyze the electronic structure and calculate their respective formation energies as a function of the change in Fermi level under bot...

The annealing kinetics of mobile intrinsic defects in cubic SiC is investigated by an ab initio method based on density-functional theory. The interstitial-vacancy recombination, the diffusion of vacancies, and interstitials to defect sinks ~e.g., surfaces or dislocations! as well as the formation of interstitial clusters are considered. The calculated migration and reaction barriers suggest a ...