Intrinsic bandgap of cleaved ZnO(112¯) surfaces

Sabitova, A.; Ebert, Ph.; Lenz, Andreas; Schaafhausen, S.; Иванова, Л. Д.; Dähne, M.; Hoffmann, A.; Dunin-Borkowski, Rafal E.; Förster, A.; Grandidier, B.; Eisele, H.

doi:10.1063/1.4776674

Cited by 9 publications

(9 citation statements)

References 37 publications

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“…Steps on the GaAs(110) surface induce defect states in the band gap, which-when present at sufficiently large concentration-induce a pinning of the Fermi energy in midgap position. 29,37 In our case, the steps have a concentration of 10 5 cm À1 on the ZB segment. This corresponds to defect state concentration of 4 Â 10 13 cm À2 assuming one defect state every lattice unit along the step edge.…”

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confidence: 75%

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Band offsets at zincblende-wurtzite GaAs nanowire sidewall surfaces

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Nys

et al. 2013

Applied Physics Letters

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The band structure and the Fermi level pinning at clean and well-ordered sidewall surfaces of zincblende (ZB)-wurtzite (WZ) GaAs nanowires are investigated by scanning tunneling spectroscopy and density functional theory calculations. The WZ-ZB phase transition in GaAs nanowires introduces p-i junctions at the sidewall surfaces. This is caused by the presence of numerous steps, which induce a Fermi level pinning at different energies on the non-polar WZ and ZB sidewall facets. V

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confidence: 75%

“…In analogy, two weak onsets (almost in the noise level) occur at þ0.6 and À0.6 V for ZB GaAs (gray arrows). Such features were shown to arise from defect states at step edges 29,36,37 suggesting a high step density.…”

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confidence: 99%

Band offsets at zincblende-wurtzite GaAs nanowire sidewall surfaces

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Nys

et al. 2013

Applied Physics Letters

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“…It has been shown recently by numerical simulation that Fermi level pinning, resulting from the presence of surface traps at the interface between ZnO and the matrix material could explain the experimentally observed length dependence [ 20 ]. The presence of surface and interface traps has been widely acknowledged in III–V and II–VI semiconductors [ 59 , 60 , 61 , 62 ]. Their impact on device operation has been explained as follows [ 20 ].…”

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confidence: 99%

Dimensional Roadmap for Maximizing the Piezoelectrical Response of ZnO Nanowire-Based Transducers: Impact of Growth Method

et al. 2021

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ZnO nanowires are excellent candidates for energy harvesters, mechanical sensors, piezotronic and piezophototronic devices. The key parameters governing the general performance of the integrated devices include the dimensions of the ZnO nanowires used, their doping level, and surface trap density. However, although the method used to grow these nanowires has a strong impact on these parameters, its influence on the performance of the devices has been neither elucidated nor optimized yet. In this paper, we implement numerical simulations based on the finite element method combining the mechanical, piezoelectric, and semiconducting characteristic of the devices to reveal the influence of the growth method of ZnO nanowires. The electrical response of vertically integrated piezoelectric nanogenerators (VING) based on ZnO nanowire arrays operating in compression mode is investigated in detail. The properties of ZnO nanowires grown by the most widely used methods are taken into account on the basis of a thorough and comprehensive analysis of the experimental data found in the literature. Our results show that the performance of VING devices should be drastically affected by growth method. Important optimization guidelines are found. In particular, the optimal nanowire radius that would lead to best device performance is deduced for each growth method.

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“…For instance, the apparent gap measured with tunneling spectroscopy can significantly differ from the intrinsic bandgap in the density of states of the sample, as it has been observed e.g. on the surfaces of Ge(111) [9], FeS 2 (100) [10] and ZnO [11]. Moreover, TIBB can also cause the ionization of donors/acceptors in the semiconductor [12][13][14], and the effect has even been used in tip-induced quantum dot experiments [15].…”

Section: Introductionmentioning

confidence: 99%

Poor electronic screening in lightly doped Mott insulators observed with scanning tunneling microscopy

et al. 2017

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The effective Mott gap measured by scanning tunneling microscopy (STM) in the lightly doped Mott insulator (Sr 1−x La x ) 2 IrO 4 differs greatly from values reported by photoemission and optical experiments. Here we show that this is a consequence of the poor electronic screening of the tip-induced electric field in this material. Such effects are well known from STM experiments on semiconductors and go under the name of tip-induced band bending (TIBB). We show that this phenomenon also exists in the lightly doped Mott insulator (Sr 1−x La x ) 2 IrO 4 and that, at doping concentrations of x 4%, it causes the measured energy gap in the sample density of states to be bigger than the one measured with other techniques. We develop a model able to retrieve the intrinsic energy gap leading to a value which is in rough agreement with other experiments, bridging the apparent contradiction.At doping x ≈ 5% we further observe circular features in the conductance layers that point to the emergence of a significant density of free carriers in this doping range and to the presence of a small concentration of donor atoms. We illustrate the importance of considering the presence of TIBB when doing STM experiments on correlated-electron systems and discuss the similarities and differences between STM measurements on semiconductors and lightly doped Mott insulators.

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Intrinsic bandgap of cleaved ZnO(112¯) surfaces

Cited by 9 publications

References 37 publications

Band offsets at zincblende-wurtzite GaAs nanowire sidewall surfaces

Band offsets at zincblende-wurtzite GaAs nanowire sidewall surfaces

Dimensional Roadmap for Maximizing the Piezoelectrical Response of ZnO Nanowire-Based Transducers: Impact of Growth Method

Poor electronic screening in lightly doped Mott insulators observed with scanning tunneling microscopy

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