Importance of carrier dynamics and conservation of momentum in atom-selective STM imaging and band gap determination of GaAs(110)

Jäger, N. D.; Weber, E. R.; Urban, K.; Ebert, Ph.

doi:10.1103/physrevb.67.165327

Cited by 39 publications

(21 citation statements)

References 35 publications

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“…This would lead to filled conduction band states from which electrons can tunnel into the tip even at voltages corresponding to energies within the band gap. [11][12][13] However, in our case, E F is pinned at 1 eV below E C and thus the tip-induced band bending would have to be larger than 1 eV in order to form an accumulation zone in the conduction band. Such large band bendings do, however, not occur at negative voltages Ͼ−5 V. Even on unpinned GaN surfaces the calculated band bending 11,13 would be Ͻ0.75 eV.…”

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Surface states and origin of the Fermi level pinning on nonpolar GaN(11¯00) surfaces

Иванова

Borisova

Eisele

et al. 2008

Applied Physics Letters

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GaN ( 1 1 ¯ 00 ) cleavage surfaces were investigated by cross-sectional scanning tunneling microscopy and spectroscopy. It is found that both the N and Ga derived intrinsic dangling bond surface states are outside of the fundamental band gap. Their band edges are both located at the Γ¯ point of the surface Brillouin zone. The observed Fermi level pinning at 1.0 eV below the conduction band edge is attributed to the high step and defect density at the surface but not to intrinsic surface states.

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confidence: 66%

“…[11][12][13] The observation of such tunnel currents requires filled semiconductor states to face empty tip states. This can only occur if ͑a͒ electrons accumulate at the GaN surface or ͑b͒ intrinsic surface states exist in the band gap.…”

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confidence: 99%

Surface states and origin of the Fermi level pinning on nonpolar GaN(11¯00) surfaces

Иванова

Borisova

Eisele

et al. 2008

Applied Physics Letters

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“…We show that the observed difference of the local height of the tunneling barrier is caused by the penetration of the electric field of the STM tip into the bulk of the sample. 28,29 This so-called tipinduced band bending is smaller on Ge-terminated areas and indicates that these areas screen the electric field of the tip more effectively.…”

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confidence: 98%

Scanning tunneling microscopy contrast in lateral Ge-Si nanostructures onSi(111)−3×3-Bi

et al. 2010

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We investigate the origin of scanning tunneling microscope ͑STM͒ contrast in lateral Ge-Si nanostructures prepared on the Si͑111͒-ͱ 3 ϫ ͱ 3-Bi surface ͓M. Kawamura, N. Paul, V. Cherepanov, and B. Voigtländer, Phys.Rev. Lett. 91, 096102 ͑2003͔͒. At low sample bias, the voltage-dependent apparent height difference between Si-and Ge-terminated areas in STM images corresponds exceptionally well to the difference in voltageintegrated scanning tunneling spectroscopy ͑STS͒ curves measured in Si-and Ge-terminated areas. The STS curves and the STM contrast reflect both differences in local density of states and in tip-induced effects in Siand Ge-terminated areas. At higher bias voltage, the tunneling into unoccupied states on Ge-terminated areas is strongly influenced by lowering of the local height of the tunneling barrier with respect to Si. The lowering of the local tunneling barrier height vanishes for the occupied states and can be traced back to different tip-induced band bending on Si-and Ge-terminated areas.

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“…4 The extent of bending is however determined by the carrier concentration in the semiconductor 4 and can lead to significant shifts in the peaks observed in the STS spectra, 9 especially in high resistivity samples. 4,6,8,20 For a 0.1 X cm n-type Si(100), the presence of a tip with a radius of 10 Å , at an applied bias of 1.5 V, will induce a band bending of 0.4 V. 9 However, the maximum band bending for a ntype Si(100)-(2 Â 1) surface can be 0.8 V. 9 The filled state p and the empty state p* bands on the (2Â 1) surface are located at 0.2 eV below the valance band maximum (VBM) and 0.4 eV below the conduction band minima (CBM), respectively, 21 which constraints the E F value at the surface between the VBM and the empty p* state. The electric field from the tip with a positive bias can locally unpin the surface and bend the band until the Fermi level meets the VBM, resulting in a maximum bending of þ0.8 V. In contrast, a negative bias on the tip results in just a small shift of þ0.09 V as the E F value is pinned at the bottom of the p* state.…”

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confidence: 99%

Spreading resistance at the nano-scale studied by scanning tunneling and field emission spectroscopy

Barimar

Naydenov

et al. 2017

Applied Physics Letters

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We explore the capability of scanning tunneling microscopy (STM) and scanning tunneling spectroscopy (STS) to study nanoscale Si(100) device layers in silicon-on-insulators (SOIs). These device layers are a macroscopic 2D silicon sheet, and understanding the effective coupling of charge in and out of this sheet allows the determination of whether it is possible to accurately measure the electronic properties of the sheet. Specifically, we examine how the spreading resistance is manifested following the processing of SOI device layers with various doping levels. Depending on the doping level, ultra-thin SOI can exhibit significant blue shifts of the peaks in the tunneling and field emission spectra. By comparing these peak shifts with the film resistivity, it is possible to estimate the contribution of the spreading resistance in STM and STS. We show that STM can be used to study the effective n-type dopant concentrations in the 1013–1016 cm−3 range. Furthermore, we demonstrate that with a sufficiently high doping level, 5 nm thick SOI device-layers can be measured and exhibit bulk like electronic characteristics.

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Importance of carrier dynamics and conservation of momentum in atom-selective STM imaging and band gap determination of GaAs(110)

Cited by 39 publications

References 35 publications

Surface states and origin of the Fermi level pinning on nonpolar GaN(11¯00) surfaces

Surface states and origin of the Fermi level pinning on nonpolar GaN(11¯00) surfaces

Scanning tunneling microscopy contrast in lateral Ge-Si nanostructures onSi(111)−3×3-Bi

Spreading resistance at the nano-scale studied by scanning tunneling and field emission spectroscopy

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