Copper impurities in bulk ZnO: A hybrid density functional study

Gallino, Federico; Valentin, Cristiana Di

doi:10.1063/1.3575198

Cited by 28 publications

(25 citation statements)

References 62 publications

(86 reference statements)

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“…This feature is consistent with previous calculations concerning hydrogen adsorption 49 and Cu doping in bulk ZnO. 50 The fact that the CBM for site b coincides with the CBMs for the other systems in Fig. 2 is thus merely coincidental.…”

Section: Electronic Properties Of the Adsorbed Cu Atomsupporting

confidence: 92%

Cu dimer formation mechanism on the ZnO(101¯0) surface

et al. 2012

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The formation of Cu dimers on the ZnO(1010) surface has been studied using hybrid density functional theory. Depending on the adsorption site, Cu atoms are found to adsorb with either oxidation state 0 or +1. In the latter case, the Cu atom has donated an electron to the ZnO conduction band. The two modes of adsorption display similar stability at low coverages, while at higher coverages the neutral species is more stable. Single Cu atoms diffuse across the ZnO(1010) surface with small barriers of migration (0.3-0.4 eV) along ZnO[1210], repeatedly switching their oxidation states, while the barrier along ZnO[0001] is significantly higher (>1.5 eV). The formation of a Cu dimer from two adsorbed Cu atoms is energetically favorable with two competing structures of similar stability, both being charge neutral. The minimum energy paths for Cu atom diffusion and dimer formation are characterized by at least one of the two Cu atoms being in oxidation state 0.

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Section: Electronic Properties Of the Adsorbed Cu Atomsupporting

confidence: 92%

Cu dimer formation mechanism on the ZnO(101¯0) surface

et al. 2012

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“…An acceptor level in the upper portion of the band gap may act as an electron trap but cannot produce p-type conductivity. More recent calculations that utilized hybrid density functional theory (DFT) 32 showed an acceptor level 2.7 eV above the VB, qualitatively consistent with the experimental data.…”

Section: A Coppersupporting

confidence: 72%

Acceptors in ZnO

McCluskey

Corolewski

et al. 2015

Journal of Applied Physics

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Zinc oxide (ZnO) has potential for a range of applications in the area of optoelectronics. The quest for p-type ZnO has focused much attention on acceptors. In this paper, Cu, N, and Li acceptor impurities are discussed. Experimental evidence indicates these point defects have acceptor levels 3.2, 1.4, and 0.8 eV above the valence-band maximum, respectively. The levels are deep because the ZnO valence band is quite low compared to conventional, non-oxide semiconductors. Using MoO 2 contacts, the electrical resistivity of ZnO:Li was measured and showed behavior consistent with bulk hole conduction for temperatures above 400 K. A photoluminescence peak in ZnO nanocrystals is attributed to an acceptor, which may involve a Zn vacancy. High field (W-band) electron paramagnetic resonance measurements on the nanocrystals revealed an axial center with g ? ¼ 2.0015 and g == ¼ 2.0056, along with an isotropic center at g ¼ 2.0035. V C 2015 AIP Publishing LLC. [http://dx.

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“…The HREELS results were further corroborated by DFT calculations [76,216]. It was found that the shallow donor states result from the interstitial Cu þ species (see Fig.…”

Section: Cu/znosupporting

confidence: 65%

Vibrational spectroscopic studies on pure and metal‐covered metal oxide surfaces

Noei

Jin

Qiu

et al. 2013

Physica Status Solidi (b)

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234 3214182 y These authors contributed equally to this work.Metal oxides and metal nanoparticles dispersed on oxide substrates have gained increasing interest in surface science because of their widespread applications, especially in heterogeneous catalysis. In this review we summarize our recent vibrational spectroscopic studies on pure and metal-covered oxide surfaces (ZnO, TiO 2 , Au/ZnO and Cu/ZnO) using a number of small molecules (H 2 , CO, CO 2 , NO and HCOOH) as probes and/or reactants. High-resolution electron energy loss spectroscopy (HREELS) turned out to be a powerful tool to investigate well-defined oxide and metal/oxide model systems. The application of a novel ultrahigh vacuum IR spectroscopy (UHV-FTIRS) apparatus allowed us to record high-quality IR data on oxide surfaces of both single crystals and polycrystalline powder particles. We will particularly focus on following important issues: (i) the interaction of hydrogen with ZnO; (ii) structure and reactivity of polar and nonpolar ZnO surfaces; (iii) the role of defects in surface chemistry of oxides; (iv) the origin of significant difference in photocatalytic activity between anatase and rutile TiO 2 and (v) the interaction between metal nanoparticles and oxide supports. We will demonstrate that the data from HREELS and UHV-FTIRS provide detailed insight into structural, electronic and chemical properties of the studied systems.

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Copper impurities in bulk ZnO: A hybrid density functional study

Cited by 28 publications

References 62 publications

Cu dimer formation mechanism on the ZnO(101¯0) surface

Cu dimer formation mechanism on the ZnO(101¯0) surface

Acceptors in ZnO

Vibrational spectroscopic studies on pure and metal‐covered metal oxide surfaces

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