Defect structure and electronic donor levels in stannic oxide crystals

Samson, Sherry D.; Fonstad, Clifton G.

doi:10.1063/1.1662011

Cited by 378 publications

(194 citation statements)

References 9 publications

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“…The calculated migration energy barrier is as low as 0.57 eV, implying that H i is mobile even below room temperature. Although additional barriers may be involved in removing H i from the samples or neutralizing its electrical activity, the high mobility of H i at relatively low temperatures indicates that it is unlikely to be the primary unintentional donor, contrary to previous suggestions [6,29]. Importantly, the observed dependence of conductivity on oxygen partial pressure [6] cannot be explained by invoking H i , since its formation energy does not depend on O .…”

Section: Prl 101 055502 (2008) P H Y S I C a L R E V I E W L E T T Econtrasting

confidence: 51%

“…However, as-grown SnO 2 exhibits n-type conductivity even when not intentionally doped [5][6][7][8]. We therefore focus specifically on hydrogen, which is commonly present in (and difficult to exclude from) the various growth and processing environments.…”

Section: Prl 101 055502 (2008) P H Y S I C a L R E V I E W L E T T Ementioning

confidence: 99%

“…Asgrown SnO 2 generally exhibits high levels of unintentional n-type conductivity [5][6][7][8]. Because this conductivity varies inversely with the oxygen partial pressure, it has been commonly attributed to the presence of native point defects, in particular, to oxygen vacancies [3,[5][6][7].…”

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confidence: 99%

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Sources of Electrical Conductivity inSnO2

et al. 2008

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SnO 2 is widely used as a transparent conductor and sensor material. Better understanding and control of its conductivity would enhance its performance in existing applications and enable new ones, such as in light emitters. Using density functional theory, we show that the conventional attribution of n-type conductivity to intrinsic point defects is incorrect. Unintentional incorporation of hydrogen provides a consistent explanation of experimental observations. Most importantly, we find that SnO 2 offers excellent prospects for p-type doping by incorporation of acceptors on the Sn site. Specific strategies for optimizing acceptor incorporation are presented.

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Section: Prl 101 055502 (2008) P H Y S I C a L R E V I E W L E T T Econtrasting

confidence: 51%

Section: Prl 101 055502 (2008) P H Y S I C a L R E V I E W L E T T Ementioning

confidence: 99%

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Sources of Electrical Conductivity inSnO2

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“…The oxygen defects were created by the reaction with the reducing gases and removed by the adsorption of oxygen. 29 The R decreased with the increase in the partial pressures To determine which of the proposed hypotheses is correct, the local Pt structures were investigated using XAFS.…”

Section: Catalytic Activity Of Pt/snomentioning

confidence: 99%

Characterization of Pt-doped SnO2 catalyst for a high-performance micro gas sensor

Murata

Suzuki

Kobayashi

et al. 2013

Phys. Chem. Chem. Phys.

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The atomic scale structure and its dependence on Pt concentration of a Pt-doped SnO 2 (Pt/SnO 2 ) thin film produced by a sputter-deposition method was investigated，which showed a high-performance methane gas sensor. Extended X-ray absorption fine structure (EXAFS) and X-ray diffraction (XRD) analyses showed that Pt/SnO 2 has a rutile structure similar to SnO 2 crystals at less than 10 at% Pt where the Pt ion was located at the Sn position in the rutile structure. There was no evidence that Pt metal clusters were formed in the Pt/SnO 2 films. The Pt/SnO 2 structure became amorphous at greater than 11 at% Pt. We found a good correlation between the methane activity and local structure of Pt.

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“…In fact, with recent advances in growth techniques, particularly perhaps the advent of novel schemes of molecular beam epitaxy, it has become possible to grow thin-films of oxide materials, as required for device applications, with rather high structural quality [34][35][36][37][38][39][40]. Notwithstanding this, however, oxygen vacancies have long been [41], and commonly still are, attributed as the primary cause of conductivity in TCOs. However, this remains a contentious issue, as discussed below.…”

Section: Native Defectsmentioning

confidence: 99%

Conductivity in transparent oxide semiconductors

King

Veal

2011

J. Phys.: Condens. Matter

225

180

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Abstract. Despite an extensive research effort for over 60 years, an understanding of the origins of conductivity in wide band-gap transparent conducting oxide (TCO) semiconductors remains elusive. While TCOs have already found widespread use in device applications requiring a transparent contact, there are currently enormous efforts to (i) increase the conductivity of existing materials, (ii) identify suitable alternatives, and (iii) attempt to gain semiconductor-engineering levels of control over their carrier density, essential for the incorporation of TCOs into a new generation of multifunctional transparent electronic devices. These efforts, however, are dependent on a microscopic identification of the defects and impurities leading to the high unintentional carrier densities present in these materials. Here, we review recent developments towards such an understanding. While oxygen vacancies are commonly assumed to be the source of the conductivity, there is increasing evidence that this is not a sufficient mechanism to explain the total measured carrier concentrations. In fact, many studies suggest that oxygen vacancies are deep, rather than shallow, donors, and their abundance in as-grown material is also debated. We discuss other potential contributions to the conductivity in TCOs, including other native defects, their complexes, and in particular hydrogen impurities. Convincing theoretical and experimental evidence is presented for the donor nature of hydrogen across a range of TCO materials, and while its stability and the presence of interstitial and substitutional species are still somewhat open questions, it is one of the leading contenders for unintentional conductivity in TCOs. We also review recent work indicating that the surfaces of TCOs can support very high carrier densities, opposite to the case of conventional semiconductors. In thin-film materials/devices and, in particular, nanostructures, the surface can have a large impact on the total conductivity in TCOs. We discuss models that attempt to explain both the bulk and surface conductivity based on features of the bulk band structure common across the TCOs, and compare these materials to other semiconductors. Finally, we briefly consider transparency in these materials, and its interplay with conductivity. Understanding this interplay, as well as the microscopic contenders for the conductivity of these materials, will prove essential to the future design and control of TCO semiconductors, and their implementation into novel multifunctional devices.

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Defect structure and electronic donor levels in stannic oxide crystals

Cited by 378 publications

References 9 publications

Sources of Electrical Conductivity inSnO2

Sources of Electrical Conductivity inSnO2

Characterization of Pt-doped SnO2 catalyst for a high-performance micro gas sensor

Conductivity in transparent oxide semiconductors

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