Variations of work function and surface conductivity on clean cleaved zinc oxide surfaces by annealing and by hydrogen adsorption

Moormann, H.; Köhl, D.; Heiland, G.

doi:10.1016/0167-2584(80)90256-x

Cited by 8 publications

(6 citation statements)

References 16 publications

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“…127 (3) Surface Band Bending Reversible changes in band bending at surfaces of conducting oxide are the basis for the chemical sensors 49,102 and have been studied for decades. [128][129][130] Recently, Lany et al demonstrated a surface accumulation layer at In 2 O 3 surfaces, induced by the reduced formation enthalpy of oxygen vacancies at the surface. 131 The accumulation layer was invoked to explain controversial observations of high electrical conductivity in nominally undoped In 2 O 3 .…”

Section: Surface Propertiesmentioning

confidence: 99%

See 1 more Smart Citation

Transparent Conducting Oxides: Electronic Structure–Property Relationship from Photoelectron Spectroscopy with in situ Sample Preparation

Klein

2012

J. Am. Ceram. Soc.

134

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The various applications of transparent conducting oxides (TCO), e.g., as electrodes in flat panel displays and solar cells or as low‐emissivity coatings have stimulated extensive research on their fabrication and properties. Recent experimental and theoretical studies of defect properties have considerably improved the understanding of the limitations of the electrical conductivity of both n‐ and p‐type transparent conductors and of the structural and electronic surface properties of the most important TCO materials. Development of emerging and future applications in the area of transparent thin film electronics with oxide semiconductors as well as the improvement of existing applications require a detailed control of the Fermi level position in the bulk and at surfaces and interfaces of polycrystalline and amorphous TCO materials. This feature article describes how the important parameters for such control can be identified using photoelectron spectroscopy with in situ sample preparation. The parameters influencing doping, work functions, ionization potentials, and surface band bending as well as energy band alignment at interfaces are described and discussed providing a fundamental understanding of important material properties for tailoring TCOs in electronic devices.

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Section: Surface Propertiesmentioning

confidence: 99%

“…Reversible changes in band bending at surfaces of conducting oxide are the basis for the chemical sensors and have been studied for decades . Recently, Lany et al .…”

Section: Surface Propertiesmentioning

confidence: 99%

Transparent Conducting Oxides: Electronic Structure–Property Relationship from Photoelectron Spectroscopy with in situ Sample Preparation

Klein

2012

J. Am. Ceram. Soc.

134

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“…The strong deviation of the observed 1/3 surface charge reduction from the ideal value of 1/4 is explained by the authors by, presumably, partial compensation of the ionic charge of Zn cations by hydrogen adsorbed on top of double Zn rows forming hydrides. On the O face, LEED, 4,7,8 lowenergy ion scattering (LEIS), 9 GIXD, 10−12 and surface X-ray diffraction 10 again showed an unreconstructed (1 × 1) structure, whereas a (1 × 3) (0001̅ ) reconstruction with O vacancies lying in the [100] direction was observed using HAS and LEED. 1,20 The O face reconstruction was supported by an X-ray photoelectron spectroscopy (XPS) quantitative analysis of the O 1s intensities, where a deficiency of 39 ± 10% of the topmost O ions was found.…”

Section: ■ Introductionmentioning

confidence: 99%

Why Are Polar Surfaces of ZnO Stable?

et al. 2017

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We probe and rationalize the complex surface chemistry of wurtzite ZnO by employing interatomic potential calculations coupled with a Monte Carlo procedure that sampled over 0.5 million local minima. We analyze the structure and stability of the ( 0001) and (0001̅ ) ZnO surfaces, rationalizing previous patterns found in STM images and explaining the (1 × 1) periodicity reported by LEED analysis. The full range of Zn/O surface occupancies was covered for a (5 × 5) supercell, keeping |m Zn − m O |/N ≈ 0.24 where m and N are the numbers of occupied surface sites and total surface sites, respectively. Our calculations explain why the (5 × 5) reconstructions seen in some experiments and highlight the importance of completely canceling the inherent dipole of the unreconstructed polar surfaces. The experimentally observed rich reconstruction patterns can be traced from the lowest occupancy, showing the thermodynamically most stable configurations of both polar surfaces. Triangular and striped reconstructions are seen, inter alia, on both polar surfaces, and hexagonal patterns also appear on the O terminated surface. Our results explain the main experimental structures observed on these complex surfaces. Moreover, grand canonical simulations of ZnO polar surfaces reveal that disorder is favored and, thus, configurational entropic factors is the the cause of their stability.

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“…However, due to the lattice mismatch between ZnO and Si, many defects appear at the ZnO/Si interface and the ZnO surface. These surface states cause Fermi-level pinning in the middle of the band gap, significantly influencing the properties of ZnO Schottky diodes [14], [15]. Therefore, many surface-treatment techniques have been proposed to modify the ZnO surface, such as oxygen plasma [8], [10] and hydrogen peroxide treatment [11], [12].…”

Section: Introductionmentioning

confidence: 99%

Non-Surface-Treated Au/ZnO Schottky Diodes Using Pre-Annealed Hydrothermal or Sol-Gel Seed Layer

Hwang

Kung

Lin

2013

IEEE Trans. Nanotechnology

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Nonsurface-treated zinc oxide (ZnO) Schottky diodes were fabricated on a Si substrate using one of two different seed layers, prepared by either the sol-gel or hydrothermal method. Then, ZnO film was grown on a seed layer by the hydrothermal method, and Au/ZnO Schottky diodes were fabricated to study the effects of different seed layers on the electric behavior. Observations show that the Schottky diodes grown on a hydrothermal seed layer exhibit very good rectifying behavior with a rectification ratio as large as 8000 at a bias voltage of ±2 V. In contrast, an ohmic behavior is observed in the Schottky diodes with sol-gel seed layer. Capacitance-voltage measurements demonstrate that the Schottky diodes grown on the hydrothermal seed layer have a Schottky barrier height of 0.77 eV as a result of Zn vacancies. However, a surface downward band bending is obtained in the ZnO grown on the sol-gel seed layer. The downward band bending renders a high carrier concentration on the ZnO surface, which is caused by the oxygen vacancies. Atomic ratio of Zn/O was investigated using Xray photoelectron spectroscopy and carrier transport mechanism was studied by current-voltage measurement.

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Variations of work function and surface conductivity on clean cleaved zinc oxide surfaces by annealing and by hydrogen adsorption

Cited by 8 publications

References 16 publications

Transparent Conducting Oxides: Electronic Structure–Property Relationship from Photoelectron Spectroscopy with in situ Sample Preparation

Transparent Conducting Oxides: Electronic Structure–Property Relationship from Photoelectron Spectroscopy with in situ Sample Preparation

Why Are Polar Surfaces of ZnO Stable?

Non-Surface-Treated Au/ZnO Schottky Diodes Using Pre-Annealed Hydrothermal or Sol-Gel Seed Layer

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