Site localization of Cd impurities in sapphire

Darriba, G. N.; Rentería, M.; Petrilli, Helena Maria; Assali, L. V. C.

doi:10.1103/physrevb.86.075203

Cited by 31 publications

(31 citation statements)

References 79 publications

(81 reference statements)

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“…The first point to take into account in this problem is the charge state of the impurity system. 38,40,[64][65][66][67] Since the valence of Cd is 2+, when a Cd atom replaces a Ln +3 atom in the structure, there is one electron less to fill the O-2p band. The presence of the Cd impurity induces the appearance of a Cd-d character acceptor level at E F , and the resulting system is metallic, as can be seen in Fig.…”

Section: B Cd-doped Ln 2 Omentioning

confidence: 99%

AbinitioLSDA and LSDA+Ustudy of pure and Cd-doped cubic lanthanide sesquioxides

et al. 2013

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The electronic, structural, and hyperfine properties of pure and Cd-doped lanthanide (Ln) sesquioxides with the cubic bixbyite structure (Ln 2 O 3 , Ln ranging from La to Lu) have been studied using the full-potential augmented plane wave plus local orbital (APW + lo) method within the local spin density approximation (LSDA) and the Coulomb-corrected LSDA + U . In the case of the pure systems, our calculations show that LSDA + U gives a better representation of the band structure compared to LSDA. The predicted equilibrium structures and the electric field gradient (EFG) tensor at Ln sites were calculated and compared with those obtained by means of hyperfine techniques and with theoretical results obtained in In 2 O 3 , Sc 2 O 3 , and Lu 2 O 3 reported in the literature. The origin of the EFG at Ln sites and the role played by the 4f electrons on this quantity are discussed. In the case of the Cd-doped systems, the APW + lo method (also within LSDA and LSDA + U ) was applied to treat the electronic structure of the doped system. The role of the Ln 4f electrons on the EFG at Cd impurity sites, and other variables like structural distortions induced by the Cd impurity, were investigated in detail and are discussed and compared with available experimental results. An excellent agreement between the experimental and calculated EFGs was found for all Cd-doped systems.

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Section: B Cd-doped Ln 2 Omentioning

confidence: 99%

AbinitioLSDA and LSDA+Ustudy of pure and Cd-doped cubic lanthanide sesquioxides

et al. 2013

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“…The defect formation energies (E df ) have been calculated using the formula shown in Equation 1. [44][45] ]…”

Section: Resultsmentioning

confidence: 99%

Defect induced room temperature ferromagnetism in methylammonium lead iodide perovskite

et al. 2020

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The defect tolerance nature of organic-inorganic hybrid perovskite is reflected from its stupendous growth in photovoltaic performances. The presence of lattice defect can manipulate or even gives rise to some exceptional properties which otherwise would have remained unseen.One of such properties reported in this article is the experimental observation of defect mediated room temperature ferromagnetism in methylammonium lead halide perovskite for the very first time, ably supported by ab-initio calculations. Theoretical analysis predicts the ferromagnetism principally arises from the iodide vacancies in the orthorhombic and cubic crystal phases but not in the tetragonal phase. The low temperature (100 K) ferromagnetic hysteresis loop was stable even at a high temperature of 380 K substantiating the fact that the origin of magnetism embedded in its defective nature.

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“…76 and 24 k-points in the irreducible Brillouin zone were used for the GaN simple cell and for the 3 × 3 × 2 supercell with the Ta impurity, respectively. Different charge states were considered for the supercell with Ta probes, where removed charges were compensated by adding a homogeneous background of opposite charge to keep the entire cell in a neutral state 27,30,31 . For instance, if an electron is removed from the cell, the extra positive charge (the hole) can be localized but a uniform negative charge will maintain the neutrality of the cell whilst not resulting in any extra interactions.…”

Section: Methodsmentioning

confidence: 99%

Studying electronic properties in GaN without electrical contacts using γ-γ vs e−-γ Perturbed Angular Correlations

Barbosa

Correia

Lorenz

et al. 2019

Sci Rep

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The potential use of combined e−-γ vs γ-γ Perturbed Angular Correlations (PAC) experiments as a possible alternative to study electronic properties of materials and/or samples where Hall effect measurements are difficult to perform due to low-quality ohmic contacts is here demonstrated using Si- and Zn-doped GaN samples as a showcase example. To do so, the lattice site of implanted 181Hf/181Ta and the recombination of Ta ionized and excited electronic states were studied as a function of temperature and sample doping in GaN. By combining the γ-γ and e−-γ PAC results with Density Functional Theory simulations, it was possible to assign a single stable site with a double-donor character for Ta in GaN. A metastable charge state was also identified at particular temperatures using e−-γ PAC. A thermally activated process was observed for the electronic recombination at high temperatures with activation energies of 15(2) meV and 12(1) meV for the Si- and Zn-doped samples, respectively, and attributed to Si shallow donors present in both samples. A reduced number of available electrons was observed in the Zn-doped sample due to donor compensation by the Zn acceptors. At low temperatures, it is suggested that the recombination process occurs via Variable Range Hopping. The doping characteristics of both samples were successfully distinguished.

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Site localization of Cd impurities in sapphire

Cited by 31 publications

References 79 publications

AbinitioLSDA and LSDA+Ustudy of pure and Cd-doped cubic lanthanide sesquioxides

AbinitioLSDA and LSDA+Ustudy of pure and Cd-doped cubic lanthanide sesquioxides

Defect induced room temperature ferromagnetism in methylammonium lead iodide perovskite

Studying electronic properties in GaN without electrical contacts using γ-γ vs e−-γ Perturbed Angular Correlations

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