Origins of the<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:mi>p</mml:mi></mml:math>-type nature and cation deficiency in<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:mrow><mml:msub><mml:mi mathvariant="normal">Cu</mml:mi><mml:mn>2</mml:mn></mml:msub><mml:mi mathvariant="normal">O</mml:mi></mml:mrow></mml:math>and related materials

Raebiger, Hannes; Lany, Stephan; Zunger, Alex

doi:10.1103/physrevb.76.045209

Cited by 494 publications

(326 citation statements)

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“…Nevertheless, as we have shown in Ref. [26], the O-p dangling bonds lie inside the band gap in a standard GGA calculation, which suggests that V Zn could bind up to 4 holes, one at each O neighbor, if the delocalization due to the self-interaction error is avoided. Indeed, applying the present method to V Zn we find that all charge states from +2, ..., −2 lie within the gap, with the respective transition levels being located at 0.45, 0.99, 1.46, and 1.91 eV above the VBM.…”

Section: Hole-binding Of V Zn In Znomentioning

confidence: 97%

Polaronic hole localization and multiple hole binding of acceptors in oxide wide-gap semiconductors

2009

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Acceptor-bound holes in oxides often localize asymmetrically at one out of several equivalent oxygen ligands. Whereas Hartree-Fock (HF) theory overly favors such symmetry-broken polaronic holelocalization in oxides, standard local density (LD) calculations suffer from spurious delocalization among several oxygen sites. These opposite biases originate from the opposite curvatures of the energy as a function of the fractional occupation number n, i.e., < 0 in HF and > 0 in LD. We recover the correct linear behavior, = 0, that removes the (de)localization bias by formulating a

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Section: Hole-binding Of V Zn In Znomentioning

confidence: 97%

Polaronic hole localization and multiple hole binding of acceptors in oxide wide-gap semiconductors

2009

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“…This occurs in Cu 2 O, for example, which is p-type due to intrinsic defects that produce hole states. While these holes are relatively mobile, the band gap of Cu 2 O is only 2.1 eV, [4] which is too low for a TCO. Cu-based delafossites, such as CuAlO 2 [5], have larger gaps due to the 2D nature of their crystal structure, but their application as TCOs is impaired by their low hole mobility which is also a result of the layered structure.…”

Section: Introductionmentioning

confidence: 99%

First-principles study of band alignments in the p-type hosts BaM₂X₂(M= Cu, Ag;X= S, Se)

Krishnapriyan

Barton

Miao

et al. 2014

J. Phys.: Condens. Matter

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Abstract. The electronic structures of four semiconductor compounds BaCu 2 S 2 , BaCu 2 Se 2 , BaAg 2 S 2 , and BaAg 2 Se 2 are studied by density functional theory using both semi-local and hybrid functionals. The ionization energies and electron affinities were determined by aligning the electronic states with the vacuum level by calculating the electrostatic profile within a supercell slab model. The ionization energy and electron affinity of the compounds were calculated using the Heyd-Scuseria-Ernzerhof (HSE) functionals and range from 4.5 to 5.4 eV and 3.1 to 3.4 eV, respectively. The replacement of Cu by Ag slightly increases the ionization energy and electron affinity, while the replacement of S by Se decreases the ionization energy but slightly increases the electron affinity. Overall, the low ionization energies and small electron affinities suggest that these compounds possess good p-type doping propensities. The band gaps are somewhat small to be ideal candidates for transparent semiconducting behavior. The replacement of Cu with Ag in the barium sulfide compounds can increase the band gap from 1.62 eV to 2.01 eV.

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“…An alternative solution can be found through application of an orbital dependent potential to control the band gap of ZnO and the Co d-d splitting independently. This could be done by either adding a Christensen potential [24,25] or by applying a Coulomb U on both the s and d orbitals to further raise the CBM level [26,27]. Through the application of DFT U d=s we can obtain an electronic structure description consistent with experiment; however, other approaches can also be used to correct the DFT band errors, and the magnetic physical picture discussed in this paper is not affected by the method used.…”

Section: Prl 100 256401 (2008) P H Y S I C a L R E V I E W L E T T Ementioning

confidence: 99%

Theoretical Description of Carrier Mediated Magnetism in Cobalt Doped ZnO

2008

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Substitutional cobalt in ZnO has a weak preference for antiferromagnetic ordering. Stabilization of ferromagnetism is achieved through n-type doping, which can be understood through a band coupling model. However, the description of the transition to a ferromagnetic ground state varies within different levels of band theory; issues arise due to the density functional theory underestimation of the band gap of ZnO, and the relative position of the nominally unfilled Co t 2d states. We examine these limitations, including approaches to overcome them, and explain the contradictions in previous studies, which drastically overestimate the doping threshold for magnetic ordering. DOI: 10.1103/PhysRevLett.100.256401 PACS numbers: 71.20.Nr, 71.15.Mb, 75.10.ÿb, 75.50.Pp The potential to simultaneously tune both charge and spin in solid state materials has lead to great interest in the field of spintronics [1]. The ultimate aim is a controllable room temperature semiconducting ferromagnet, which could be used in magnetoelectric and magnetotransport devices. Intrinsically magnetic semiconductors generally possess relatively low Curie temperatures (T C ); however, it has been proposed that incorporating transition metal or rare earth ions into a nonmagnetic semiconductor host lattice, forming a dilute magnetic semiconductor (DMS), may help raise T C above room temperature [2,3].In DMS materials, magnetism is influenced and controlled by the presence of charge carriers in the form of holes (GaAs:Mn) or electrons (GaN:Gd). There is still great debate over the fundamental mechanism behind the origin of the observed high temperature magnetic alignment in many of these systems. The situation is not helped by large variation in both experimental and theoretical studies [4 -8].Cobalt doped ZnO has become a focus of attention due to its reported high T C of up to 700 K and, most promisingly, the reversible cycling of FM ordering [9]. Coupled with existing optical and electrical properties of ZnO, the addition of controllable magnetism could make it a technologically essential material. It has been reported that at Co concentrations of less than 10%, the solubility is good and Co occupies a substitutional Zn site in a 2 charge state [9,10]. B . The splitting between filled e d and empty minority t 2d states for tetrahedral Co is typically on the order of 1.5-2 eV [12]. In a wide gap semiconductor such as ZnO (E g 3:4 eV), this would place the minority spin Co t 2d states within the band gap, as has been reported from both optical and magnetic measurements for ZnO:Co [13][14][15]. Surprisingly, this is not the case in previous theoretical studies [5][6][7][8].From consideration of Co 3d band coupling, FM interactions between occupied majority t 2d states results in no net energy gain due to filled bonding and antibonding combinations, while AFM interactions can result in a small energy gain (Fig. 1). Partial occupation of the empty minority t 2d states will result in a transition to FM ordering through the energy gained from the fi...

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Origins of thep-type nature and cation deficiency inCu2Oand related materials

Cited by 494 publications

References 25 publications

Polaronic hole localization and multiple hole binding of acceptors in oxide wide-gap semiconductors

Polaronic hole localization and multiple hole binding of acceptors in oxide wide-gap semiconductors

First-principles study of band alignments in the p-type hosts BaM₂X₂(M= Cu, Ag;X= S, Se)

Theoretical Description of Carrier Mediated Magnetism in Cobalt Doped ZnO

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Origins of thep-type nature and cation deficiency inCu2Oand related materials

Cited by 494 publications

References 25 publications

Polaronic hole localization and multiple hole binding of acceptors in oxide wide-gap semiconductors

Polaronic hole localization and multiple hole binding of acceptors in oxide wide-gap semiconductors

First-principles study of band alignments in the p-type hosts BaM2X2(M= Cu, Ag;X= S, Se)

Theoretical Description of Carrier Mediated Magnetism in Cobalt Doped ZnO

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First-principles study of band alignments in the p-type hosts BaM₂X₂(M= Cu, Ag;X= S, Se)