Diffusion Study of Chlorine in SiC by First Principles Calculations

2013 ◽  
Vol 740-742 ◽  
pp. 381-384
Author(s):  
Giovanni Alfieri ◽  
Tsunenobu Kimoto
Keyword(s):  
First Principles ◽  
First Principles Calculations ◽  
Diffusion Study ◽  
P Type ◽  
Formation Energies

Using first-principles calculations, we investigated the migration mechanisms of Cl in cubic SiC. The analysis of the formation energies of several defect configurations (isolated interstitials and complex defects), either reported in the literature or calculated in the present study, revealed that three migration mechanisms are possible: Interstitialcy and two different vacancy-mediated mechanisms (both concerted exchange and second-neighbor hop). Our calculations showed that vacancy-mediated diffusion is more energetically favorable than an intersticialcy one and the values of the diffusivity, for both n-type and p-type SiC were also estimated.

First-principles calculations of intrinsic defects in the p-type semiconductor CuAlO2

2010 ◽  
Vol 88 (12) ◽  
pp. 927-932 ◽  
Author(s):  
Dan Huang ◽  
Yuanming Pan
Keyword(s):  
First Principles ◽  
Defect Formation ◽  
First Principles Calculations ◽  
Image Charge ◽  
Intrinsic Defects ◽  
Type Conductivity ◽  
The Poor ◽  
Type Semiconductor ◽  
P Type ◽  
Formation Energies

Intrinsic defects, including vacancies at the Cu and Al sites (VCu and VAl), substitutional Cu at the Al site (CuAl), and interstitial O (Oi), have been proposed to be responsible for the p-type conductivity in CuAlO2. We have investigated the formation energies of these and other intrinsic defects in CuAlO2 using GGA+U calculations. Our results support previous studies that the potential alignment and image charge correction are required in the calculation of defect formation energies by using the supercell approach. In CuAlO2, these p-type defects (VCu, VAl, CuAl, and Oi) invariably have lower formation energies than their n-type counterparts. Particularly, VCu and CuAl have the lowest formation energies among intrinsic defects, and therefore are most likely responsible for the p-type conductivity. However, the transition levels of the VCu and CuAl defects are deep, which are responsible for the poor p-type conductivity in CuAlO2.

Defect formation of CuI-doped by group-IIB elements

2019 ◽  
Vol 33 (01) ◽  
pp. 1850423
Author(s):  
Hui Chen ◽  
Mu Gu
Keyword(s):  
First Principles ◽  
Formation Energy ◽  
Defect Formation ◽  
Valence Band Maximum ◽  
Acceptor Level ◽  
First Principles Calculations ◽  
Transition Energies ◽  
Band Maximum ◽  
P Type ◽  
Formation Energies

First-principles calculations have been performed to investigate the doping defects in CuI with group-IIB elements such as Zn, Cd and Hg. The calculated transition energies for substitutional Zn, Cd and Hg are 1.32, 1.28 and 0.60 eV, respectively. These group-IIB elements at the substitutional sites complex with a copper vacancy [Formula: see text] have the lower formation energies as compared to dopants located at the substitutional sites or interstitial sites, respectively. Among all the complex defects considered, [Formula: see text] has the lowest formation energy and it induces the acceptor level [Formula: see text] eV above the valence-band maximum (VBM), which is close to the acceptor level [Formula: see text] eV of [Formula: see text], suggesting that Hg may be a good dopant for CuI to improve its p-type conductivity.

Defect Complexes and Non-Equilibrium Processes Underlying the P-Type Doping of GaN

1998 ◽  
Vol 537 ◽  
Author(s):  
Fernando A. Reboredo ◽  
Sokrates T. Pantelides
Keyword(s):  
High Temperature ◽  
Experimental Evidence ◽  
First Principles ◽  
Final Anneal ◽  
First Principles Calculations ◽  
Defect Complexes ◽  
Equilibrium Processes ◽  
Open Questions ◽  
High Temperature Anneal ◽  
P Type

AbstractIt is well known that hydrogen plays a key role in p-type doping of GaN. It is believed that H passivates substitutional Mg during growth by forming a Mgs-N-Hi complex; in subsequent annealing, H is removed, resulting in p-type doping. Several open questions have remained, however, such as experimental evidence for other complexes involving Mg and H and difficulties in accounting for the relatively high-temperature anneal needed to remove H. We present first principles calculations in terms of which we show that the doping process is in fact significantly more complex. In particular, interstitial Mg plays a major role in limiting p-type doping. Overall, several substitutional/interstitial complexes form and can bind H, with vibrational frequencies that account for hitherto unidentified observed lines. We predict that these defects, which limit doping efficiency, can be eliminated by annealing in an atmosphere of H and N prior to the final anneal that removes H.

An effective and efficient approach to p-type AlN by Be2:O codoping from first-principles calculations

2016 ◽  
Vol 30 (20) ◽  
pp. 1650257
Author(s):  
Meng Zhao ◽  
Wenjun Wang ◽  
Jun Wang ◽  
Junwei Yang ◽  
Weijie Hu ◽  
...  
Keyword(s):  
First Principles ◽  
Ionization Energy ◽  
Hole Concentration ◽  
Valence Band Maximum ◽  
First Principles Calculations ◽  
Mutual Compensation ◽  
Efficient Approach ◽  
P Type ◽  
Codoping Method

Various Be:O-codoped AlN crystals have been investigated via first-principles calculations to evaluate the role of the different combinations in effectively and efficiently inducing p-type carriers. It is found that the O atom is favored to bond with two Be atoms. The formed Be2:O complexes decrease the acceptor ionization energy to 0.11 eV, which is 0.16 eV lower than that of an isolated Be in AlN, implying that the hole concentration could probably be increased by 2–3 orders of magnitude. The electronic structure of Be2:O-codoped AlN shows that the lower ionization energy can be attributed to the interaction between Be and O. The Be–O complexes, despite failing to induce p-type carriers for the mutual compensation of Be and O, introduce new occupied states on the valence-band maximum (VBM) and hence the energy needed for the transition of electrons to the acceptor level is reduced. Thus, the Be2:O codoping method is expected to be an effective and efficient approach to realizing p-type AlN.

Stability and Structures of Constitutional Defects in Nonstoichiometric Intermetallic Compounds by First-Principles Calculations

2005 ◽  
Vol 475-479 ◽  
pp. 3111-3114
Author(s):  
Masataka Mizuno ◽  
Hideki Araki ◽  
Yasuharu Shirai
Keyword(s):  
Intermetallic Compounds ◽  
First Principles ◽  
Electronic Structures ◽  
Stoichiometric Composition ◽  
Electronic Structure Calculations ◽  
First Principles Calculations ◽  
Compositional Dependence ◽  
Wide Range ◽  
Formation Energies ◽  
Structure Calculations

Some of intermetallic compounds exist in a wide range of concentration around the stoichiometric composition. First-principles electronic structure calculations have been performed for constitutional defects in non-stoichiometric CoAl and CoTi in order to investigate their stabilities and structural relaxations induced by constitutional defects. For the evaluation of stabilities of constitutional defects, the compositional dependence curves both of formation energies and of lattice parameters are obtained by the calculations employing supercells in various sizes. The lattice relaxations around constitutional defects are discussed by analyzing the change in electronic structures induced by constitutional defects.

First-Principles Calculations of Titanium Dopants in Alumina

2005 ◽  
Vol 475-479 ◽  
pp. 3095-3098
Author(s):  
Katsuyuki Matsunaga ◽  
Teruyasu Mizoguchi ◽  
Atsutomo Nakamura ◽  
Takahisa Yamamoto ◽  
Yuichi Ikuhara
Keyword(s):  
Band Gap ◽  
First Principles ◽  
Electronic Structures ◽  
First Principles Calculations ◽  
Pseudopotential Calculations ◽  
Formation Energies

First-principles pseudopotential calculations were performed to investigate atomic and electronic structures of titanium (Ti) dopants in alumina (Al2O3). It was found that a substitutional Ti3+ defect induced an extra level occupied by one electron within the band gap of Al2O3. When two or more substitutional Ti3+ defects were located closely to each other, the defect-induced levels exhibited strong bonding interactions, and their formation energies decreased with increasing numbers of Ti3+ defects. This indicates that association and clustering of substitutional Ti3+ defects in Al2O3 can take place due to the interaction of the defect-induced levels.

New Pt-based Superalloy System Designed from First Principles

2008 ◽  
Vol 1128 ◽  
Author(s):  
Vsevolod I. Razumovskiy ◽  
Eyvaz I. Isaev ◽  
Andrei V. Ruban ◽  
Pavel A. Korzhavyi
Keyword(s):  
Elastic Properties ◽  
First Principles ◽  
Defect Formation ◽  
Alloy System ◽  
First Principles Calculations ◽  
Phonon Spectra ◽  
Ultrahigh Temperature ◽  
New Generation ◽  
Formation Energies ◽  
Temperature Applications

AbstractPt-Sc alloys with the γ-γ′ microstructure are proposed as a basis for a new generation of Pt-based superalloys for ultrahigh-temperature applications. This alloy system was identified on the basis of first-principles calculations. Here we discuss the prospects of the Pt-Sc alloy system on the basis of calculated elastic properties, phonon spectra, and defect formation energies.

scholarly journals Rich p -type-doping phenomena in boron-substituted silicene systems

2020 ◽  
Vol 7 (12) ◽  
pp. 200723
Author(s):  
Hai Duong Pham ◽  
Wu-Pei Su ◽  
Thi Dieu Hien Nguyen ◽  
Ngoc Thanh Thuy Tran ◽  
Ming-Fa Lin
Keyword(s):  
Charge Transfer ◽  
Fermi Level ◽  
Charge Density ◽  
Electronic Properties ◽  
First Principles ◽  
Chemical Environment ◽  
First Principles Calculations ◽  
Density Distributions ◽  
Essential Properties ◽  
P Type

The essential properties of monolayer silicene greatly enriched by boron substitutions are thoroughly explored through first-principles calculations. Delicate analyses are conducted on the highly non-uniform Moire superlattices, atom-dominated band structures, charge density distributions and atom- and orbital-decomposed van Hove singularities. The hybridized 2 p z –3 p z and [2s, 2 p x , 2 p y ]–[3s, 3 p x , 3 p y ] bondings, with orthogonal relations, are obtained from the developed theoretical framework. The red-shifted Fermi level and the modified Dirac cones/ π bands/ σ bands are clearly identified under various concentrations and configurations of boron-guest atoms. Our results demonstrate that the charge transfer leads to the non-uniform chemical environment that creates diverse electronic properties.

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