Ab initio materials design for transparent-conducting-oxide-based new-functional materials

Katayama‐Yoshida, Hiroshi; Satō, Kazunori; Kizaki, Hidetoshi; Funashima, Hiroki; Hamada, Ikutaro; Fukushima, Tetsuya; Dinh, Van An; Toyoda, Masayuki

doi:10.1007/s00339-007-4037-2

Cited by 38 publications

(27 citation statements)

References 34 publications

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“…A possible defect model has been proposed – a Li Zn –H–Li Zn complex (an acceptor–donor–acceptor complex, ADA) acting as a single acceptor 10. The pair formation as proposed in this model could result in a significant lowering of the acceptor binding energy as predicted by theory within the co‐doping concept for ZnO 36–39 and AlN 40, 41 and shown schematically in Fig. 3.…”

Section: Methodsmentioning

confidence: 90%

A model for acceptor doping in ZnO based on nitrogen pair formation

Lautenschlaeger

Hofmann

Eisermann

et al. 2011

Physica Status Solidi (b)

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We reconsider acceptor doping of ZnO with Li and Cu published nearly 40 years ago by comparing it with the behaviour of nitrogen in ZnO. While Cu plays an exceptional role due to the d-shell configuration (acceptor level at 190 meV below conduction band) Li and N as single acceptors give rise to deep distorted acceptors with binding energies between 700 and 800 meV above valence band. With these binding energies no hole conductivity at room temperature can be expected, having in mind that typical background donor densities in ZnO are between 10 16 and 10 17 cm À3 . We propose a defect model to explain the role of lithium and nitrogen doping in ZnO which is based on two acceptor-one donor pairing as proposed by theory in the framework of co-doping. Hydrogen is a key candidate for the donor role. The luminescence properties in ZnO:N can be understood on the basis of the calculation of the hole densities without and with compensation assuming pair formation. We compare our experimental findings with published results on nitrogen doped ZnO explaining the limitations of p-type doping of ZnO with nitrogen.

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Section: Methodsmentioning

confidence: 90%

A model for acceptor doping in ZnO based on nitrogen pair formation

Lautenschlaeger

Hofmann

Eisermann

et al. 2011

Physica Status Solidi (b)

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“…It suggests that the mechanism of magnetic coupling between vacancies is different from that one between transition metals in Cr and Co doped anatase. A quantitative improvment may be obtained by using the recent self‐interaction corrected (pseudo‐SIC) 16 and LDA+U 17 methods which are widely inplemented in research of DMS 18, 19.…”

Section: Energy Differences Between Ferro‐ and Anti‐ferromagnetic Alimentioning

confidence: 99%

First principle study of the cation vacancy in anatase TiO₂

Bai

Chen²

2007

Physica Rapid Research Ltrs

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Diluted magnetic semiconductors (DMS) [1] are a rapidly growing research field due to their potential applications in spintronic [2] devices. Several semiconducting oxide materials such as CaO [3], ZnO [4], HfO 2 [5], SnO 2 [6], TiO 2 [7] have been shown both experimentally and theoretically to have DMS properties. Normally there exists no magnetism in these material, but it will appear when defects exist. Introducing transition metal substitutions at the cation positions is one way to produce magnetism. Cu atoms in ZnO [4], Fe in SnO 2 [6] were verified to have ferromagnetism and high Curie temperature (T C ). Another way to obtain the high temperature ferromagnetism is doping nonmetal atoms at anion positions, such as the magnetism in N, C doped CaO [8] and C in SrO [9]. Cation intrinsic vacancy also leads to the high T C magnetism -Ca and Hf vacancies in CaO [3] and HfO 2 [5] demonstrate this kind of ferromagnetism origin. As a common wide band semiconductor, TiO 2 has also been studied as a possible DMS material. Both Co doped anatase [7] and rutile [10], and Cr [11] doped anatase TiO 2 have shown high temperature ferromagnetism. And in these transition metal impurity structures, the O vacancy plays a crucial role to ferromagnetism and structure stability [12]. In this letter, we carry out first principle calculations about cation vacancy effect on the ferromagnetism of anatase TiO 2 . Our research shows that like other ionic materials HfO 2 and CaO, the cation vacancy in anatase TiO 2 also induces ferromagnetism.The calculation in this letter is carried out with the GGA [12] exchange correlation in the frame of the full po-tential linear augmented plane wave (FP-LAPW) method using the WIEN2k package [13]. We use a 48-atom supercell in our calculation. With one or two Ti vacancies, the simulated vacancy concentration is 6.25% and 12.5%, respectively. The muffin-tin radius R is chosen to be 1.5 a.u. for the Ti atom and 2.0 a.u. for O atoms. The convergence parameter (RK) max is chosen to be 7.5, where K gives the largest number of the k-vector in the plane wave expansion. This gives well-converged basis sets consisting of approximately 23570 plane waves. Brillouin zone integrations are performed by summations over a 4 × 4 × 3 Monkhorst-Pack [15] special k-point mesh. The calculations are iterated to self-consistency when the total energy change was less than 0.00005 Ry.In anatase, one Ti atom is surrounded by six O atoms, forming a distorted octahedral structure (Fig. 1). The O atoms can be clarified into two classes. We mark them as O1 and O2.According to molecular orbital theory, the 3d and 4s electrons of Ti and the 2p electrons of O form σand π-orbitals, and when the neutral Ti atom is taken from the structure, it will introduce four holes in the molecular orbital. According to the theoretical research of CaO and HfO 2 , the holes will be arranged spin-parallel in the orbital because of Hund's coupling rules and the on-site Coulomb repulsion energy U pp between the holes. Our first principle calculation sh...

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“…Also, introducing magnetic impurities in CuAlO 2 , new diluted magnetic semiconductors can be produced. 4,5 It has also been demonstrated 6,7 that CuAlO 2 may become a good thermoelectric material with promising future applications.…”

Section: Introductionmentioning

confidence: 99%

Electronic properties of3R-CuAlO2under pressure: Three theoretical approaches

et al. 2010

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The pressure variation in the structural parameters, u and c / a, of the delafossite CuAlO 2 is calculated within the local-density approximation ͑LDA͒. Further, the electronic structures as obtained by different approximations are compared: LDA, LDA+ U, and a recently developed "quasiparticle self-consistent GW"͑QSGW͒ approximation. The structural parameters obtained by the LDA agree very well with experiments but, as expected, gaps in the formal band structure are underestimated as compared to optical experiments. The ͑in LDA too high lying͒ Cu 3d states can be down shifted by LDA+ U. The magnitude of the electric field gradient ͑EFG͒ as obtained within the LDA is far too small. It can be "fitted" to experiments in LDA+ U but a simultaneous adjustment of the EFG and the gap cannot be obtained with a single U value. QSGW yields reasonable values for both quantities. LDA and QSGW yield significantly different values for some of the band-gap deformation potentials but calculations within both approximations predict that 3R-CuAlO 2 remains an indirect-gap semiconductor at all pressures in its stability range 0-36 GPa, although the smallest direct gap has a negative pressure coefficient.

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Ab initio materials design for transparent-conducting-oxide-based new-functional materials

Cited by 38 publications

References 34 publications

A model for acceptor doping in ZnO based on nitrogen pair formation

A model for acceptor doping in ZnO based on nitrogen pair formation

First principle study of the cation vacancy in anatase TiO₂

Electronic properties of3R-CuAlO2under pressure: Three theoretical approaches

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Ab initio materials design for transparent-conducting-oxide-based new-functional materials

Cited by 38 publications

References 34 publications

A model for acceptor doping in ZnO based on nitrogen pair formation

A model for acceptor doping in ZnO based on nitrogen pair formation

First principle study of the cation vacancy in anatase TiO2

Electronic properties of3R-CuAlO2under pressure: Three theoretical approaches

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First principle study of the cation vacancy in anatase TiO₂