The study of the behavior of Al impurity in ZnO lattice by a fullerene like model

The fullerene like Zn32Al4O36 clusters were investigated and the oxygen interstitial Oi acceptor intrinsic defect formation energy as well as Al ionization energy were calculated. The effect of lattice packing defects on the electroactivity of Al impurity was investigated. Analysis of the defects formation energies shows the smaller formation energy of interstitial Oi in a comparison with a formation of Zn vacancy. This allows us to formulate recommendations of technological conditions for films deposition, with improved electroactivity of Al donor.

Investigating the existence of oxygen interstitial in CuCr1􀀀xMgxO2 [0.00 X 0.30] thermoelectric materials by X-Ray photoelectron spectroscopy [XPS]

Climate change is promoting researches on materials which is capable of converting environmentally friendly energy, in which materials that convert heat into electricity are receiving significant attention, because their ability of converting heat to electricity not only generates the electricity but also contributes to slow down the consumption of fossil fuel. The existence of point defects in the semiconductors greatly effected properties of materials, especially thermoelectric properties. Therefore, the study of defects in materials is a popular research trend today. In this study, we focus on evaluating the existence of oxygen interstitial in CuCr1􀀀xMgxO2 [0.00 x 0.30] compounds, because oxygen interstitial greatly affected the thermoelectric properties of this material. Based on X-ray photoelectron spectroscopy (XPS) analysis, at the large ratio of Mg impurity x = 0.15, the compound had the highest percentage of oxygen interstitial and was also a good thermoelectric material. In addition, it could be also seen that CuCrO2 material being doped a large Mg doping ratio (x = 0.15) was suitable for thermal-to-electrical applications rather than the ones with a small ratio (x 0.05).

Mechanism of Creation and Destruction of Oxygen Interstitial Atoms by Nonpolar Zinc Oxide(10\bar{1}0) Surfaces

Oxygen vacancies (VO) influence many properties of ZnO in semiconductor devices, yet synthesis methods leave behind variable and unpredictable VO concentrations. Oxygen interstitials (Oi) move far more rapidly, so post-synthesis...

The Interstitial Carbon–Dioxygen Center in Irradiated Silicon

We investigated, experimentally as well as theoretically, defect structures in electron irradiated Czochralski-grown silicon (Cz-Si) containing carbon. Infrared spectroscopy (IR) studies observed a band at 1020 cm−1 arisen in the spectra around 300 °C. Its growth occurs concomitantly with the decay out of the well-known vacancy-oxygen (VO) defect, with a Local Vibrational Mode (LVM) at 830 cm−1 and carbon interstitial-oxygen interstitial (CiOi) defect with a LVM at 862 cm−1, in silicon (Si). The main purpose of this work is to establish the origin of the 1020 cm−1 band. One potential candidate is the carbon interstitial-dioxygen (CiO2i) defect since it is expected to form upon annealing out of the CiOi pair. To this end, systematic density functional theory (DFT) calculations were used to predict the lowest energy structure of the (CiO2i) defect in Si. Thereafter, we employed the dipole–dipole interaction method to calculate the vibrational frequencies of the structure. We found that CiO2i defect has an LVM at ~1006 cm−1, a value very close to our experimental one. The analysis and study of the results lead us to tentatively correlate the 1020 cm−1 band with the CiO2i defect.

Ostwald Growth Rate in Controlled Covid-19 Epidemic Spreading as in Arrested Growth in Quantum Complex Matter

Here, we focus on the data analysis of the growth of epidemic spread of Covid-19 in countries where different policies of containment were activated. It is known that the growth of pandemic spread at its threshold is exponential, but it is not known how to quantify the success of different containment policies. We identify that a successful approach gives an arrested phase regime following the Ostwald growth, where, over the course of time, one phase transforms into another metastable phase with a similar free energy as observed in oxygen interstitial diffusion in quantum complex matter and in crystallization of proteins. We introduce the s factor which provides a quantitative measure of the efficiency and speed of the adopted containment policy, which is very helpful not only to monitor the Covid-19 pandemic spread but also for other countries to choose the best containment policy. The results show that a policy based on joint confinement, targeted tests, and tracking positive cases is the most rapid pandemic containment policy; in fact, we found values of 9, 5, and 31 for the success s factor for China, South Korea, and Italy, respectively, where the lowest s factor indicates the best containment policy.

Unveiling the atomic defects and electronic structure of Cu2.2Zn0.8SnSe4−xTex (x = 0 to 0.04) by X-ray absorption fine structure spectroscopy

CuZn anti-site defects and oxygen interstitial defects in a quaternary compound, Cu2.2Zn0.8SnSe4, are revealed by X-ray absorption fine structure spectroscopy.