Hydrogen on III-V (110) surfaces: Charge accumulation and STM signatures

Castleton, Christopher; Höglund, Anders; Göthelid, Mats; Qian, Meichun; Mirbt, Susanne

doi:10.1103/physrevb.88.045319

Cited by 14 publications

(12 citation statements)

References 70 publications

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“…For the current NWs, nonintentionally incorporated carbon is the main “bulk” dopant, which indeed leads to n-type doping of the NWs. , This should already suffice to explain the observed position of the Fermi level in our measurements. However, surface defects are also known to play a very significant role in the doping of NWs, not least for NWs with large surface-to-bulk ratios. , For defect-free InAs {110} surfaces, no Fermi-level pinning is observed; however in the presence of defects, Fermi-level pinning to the extent of formation of a surface 2DEG has been observed. ,, Here we point out that all these defects will be clearly observable in STM. In our case we have thus prepared our surfaces with as few defects as possible and recorded spectra as far away from any defects as could be done.…”

Section: Resultsmentioning

confidence: 63%

Electronic and Structural Differences between Wurtzite and Zinc Blende InAs Nanowire Surfaces: Experiment and Theory

et al. 2014

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We determine the detailed differences in geometry and band structure between wurtzite (Wz) and zinc blende (Zb) InAs nanowire (NW) surfaces using scanning tunneling microscopy/spectroscopy and photoemission electron microscopy. By establishing unreconstructed and defect-free surface facets for both Wz and Zb, we can reliably measure differences between valence and conduction band edges, the local vacuum levels, and geometric relaxations to the few-millielectronvolt and few-picometer levels, respectively. Surface and bulk density functional theory calculations agree well with the experimental findings and are used to interpret the results, allowing us to obtain information on both surface and bulk electronic structure. We can thus exclude several previously proposed explanations for the observed differences in conductivity of Wz-Zb NW devices. Instead, fundamental structural differences at the atomic scale and nanoscale that we observed between NW surface facets can explain the device behavior.

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Section: Resultsmentioning

confidence: 63%

Electronic and Structural Differences between Wurtzite and Zinc Blende InAs Nanowire Surfaces: Experiment and Theory

et al. 2014

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“…[9,12] Moreover, it has been recently predicted that the transfer level  +/of a H atom adsorbed on a semiconductor's surface namely, the level at which the stable H charge switches from +1 to -1 depends on the specific material investigated, in contrast to what reported in the bulk case. [13] Even more surprising are the effects that H irradiation has on the structural, electronic, and transport properties of dilute nitrides alloys, such as Ga(AsN), Ga(PN), and (InGa)(AsN). [14] The properties of the host material are severely modified by the substitution of a small percentage of the anions with N, while they are fully recovered upon hydrogenation.…”

Section: Introductionmentioning

confidence: 99%

Peculiarities of the hydrogenated In(AsN) alloy

Birindelli

Kesaria

Giubertoni

et al. 2015

Semicond. Sci. Technol.

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The electronic properties of In(AsN) before and after post-growth sample irradiation with increasing doses of atomic hydrogen have been investigated by photoluminescence. The electron density increases in In(AsN) but not in N-free InAs, until a Fermi stabilization energy is established. A hydrogen  +/transition level just below the conduction band minimum accounts for the dependence of donor formation on N, in agreement with a recent theoretical report highlighting the peculiarity of InAs among III-V compounds. Raman scattering measurements indicate the formation of N-H complexes that are stable under thermal annealing up to ~500 K. Finally, hydrogen does not passivate the electronic activity of N, thus leaving the band gap energy of In(AsN) unchanged, once more in stark contrast to what reported in other dilute nitride alloys.

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“…However, our work also raises the question of what other defects could be mistaken for an oxygen vacancy at the surface. One obvious candidate is hydrogen, which was recently shown to exhibit a similar STM appearance to anion vacancies at III-V semiconductor surfaces [42]. Hydrogen is a ubiquitous contaminant, with many sources, not least the dissociation of water molecules, which are usually present even under ultrahigh vacuum conditions.…”

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confidence: 99%

Oxygen Vacancies versus Fluorine atCeO2(111): A Case of Mistaken Identity?

et al. 2014

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We propose a resolution to the puzzle presented by the surface defects observed with STM at the (111) surface facet of CeO 2 single crystals. In the seminal paper of Esch et al. [Science 309, 752 (2005)] they were identified with oxygen vacancies, but the observed behavior of these defects is inconsistent with the results of density functional theory (DFT) studies of oxygen vacancies in the literature. We resolve these inconsistencies via DFT calculations of the properties of both oxygen vacancies and fluorine impurities at CeO 2 ð111Þ, the latter having recently been shown to exist in high concentrations in single crystals from a widely used commercial source of such samples. We find that the simulated filled-state STM images of surface-layer oxygen vacancies and fluorine impurities are essentially identical, which would render problematic their experimental distinction by such images alone. However, we find that our theoretical results for the most stable location, mobility, and tendency to cluster, of fluorine impurities are consistent with experimental observations, in contrast to those for oxygen vacancies. Based on these results, we propose that the surface defects observed in STM experiments on CeO 2 single crystals reported heretofore were not oxygen vacancies, but fluorine impurities. Since the similarity of the simulated STM images of the two defects is due primarily to the relative energies of the 2p states of oxygen and fluorine ions, this confusion might also occur for other oxides which have been either doped or contaminated with fluorine.

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Hydrogen on III-V (110) surfaces: Charge accumulation and STM signatures

Cited by 14 publications

References 70 publications

Electronic and Structural Differences between Wurtzite and Zinc Blende InAs Nanowire Surfaces: Experiment and Theory

Electronic and Structural Differences between Wurtzite and Zinc Blende InAs Nanowire Surfaces: Experiment and Theory

Peculiarities of the hydrogenated In(AsN) alloy

Oxygen Vacancies versus Fluorine atCeO2(111): A Case of Mistaken Identity?

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