Tomographic investigation of fermi level pinning at focused ion beam milled semiconductor surfaces

Wolf, Daniel; Lubk, Axel; Lenk, A.; Sturm, Sebastian; Lichte, Hannes

doi:10.1063/1.4858957

Cited by 25 publications

(11 citation statements)

References 34 publications

(36 reference statements)

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“…For instance, Wolf et al measure a built-in potential of 0.45 V in Si, whereas 1.0 V is expected. 2 The discrepancy is known to be especially large in GaN, where built-in potentials of around 3.4 V are expected, and values of 0.68 V and lower are generally found. 3,4 To some extend, these discrepancies can be explained by amorphous and defective surface layers (usually dubbed "dead" layers) formed during specimen preparation [5][6][7] or by Fermi level pinning in this defective layers.…”

mentioning

confidence: 99%

“…3,4 To some extend, these discrepancies can be explained by amorphous and defective surface layers (usually dubbed "dead" layers) formed during specimen preparation [5][6][7] or by Fermi level pinning in this defective layers. 2,8 Irradiation by the electron beam during the electron holographic experiments (usually 200-300 kV) generates electronhole pairs within the depletion region. Usually this effect is not considered as a reason for the discrepancy.…”

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confidence: 99%

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Impact of electron irradiation on electron holographic potentiometry

Park

Niermann

Berger

et al. 2014

Applied Physics Letters

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While electron holography in the transmission electron microscope offers the possibility to measure maps of the electrostatic potential of semiconductors down to nanometer dimensions, these measurements are known to underestimate the absolute value of the potential, especially in GaN. We have varied the dose rates of electron irradiation over several orders of magnitude and observed strong variations of the holographically detected voltages. Overall, the results indicate that the electron beam generates electrical currents within the specimens primarily by the photovoltaic effect and due to secondary electron emission. These currents have to be considered for a quantitative interpretation of electron holographic measurements, as their negligence contributes to large parts in the observed discrepancy between the measured and expected potential values in GaN.

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confidence: 99%

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confidence: 99%

Impact of electron irradiation on electron holographic potentiometry

Park

Niermann

Berger

et al. 2014

Applied Physics Letters

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“…The ability to measure local variations in charge density, electric field, and electrostatic potential in nanoscale materials and devices, such as doped semiconductors [1][2][3][4] and nanoscale field emitters, [5][6][7][8] in the transmission electron microscope (TEM) is important for understanding the relationship between internal microstructure, chemistry, defects, and functional properties.…”

Section: Introductionmentioning

confidence: 99%

Model-independent measurement of the charge density distribution along an Fe atom probe needle using off-axis electron holography without mean inner potential effects

Migunov

London

Farle

et al. 2015

Journal of Applied Physics

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Towards quantitative off-axis electron holographic mapping of the electric field around the tip of a sharp biased metallic needle J. Appl. Phys. 116, 024305 (2014) Model-independent measurement of the charge density distribution along an Fe atom probe needle using off-axis electron holography without mean inner potential effects The one-dimensional charge density distribution along an electrically biased Fe atom probe needle is measured using a model-independent approach based on off-axis electron holography in the transmission electron microscope. Both the mean inner potential and the magnetic contribution to the phase shift are subtracted by taking differences between electron-optical phase images recorded with different voltages applied to the needle. The measured one-dimensional charge density distribution along the needle is compared with a similar result obtained using model-based fitting of the phase shift surrounding the needle. On the assumption of cylindrical symmetry, it is then used to infer the three-dimensional electric field and electrostatic potential around the needle with $10 nm spatial resolution, without needing to consider either the influence of the perturbed reference wave or the extension of the projected potential outside the field of view of the electron hologram. The present study illustrates how a model-independent approach can be used to measure local variations in charge density in a material using electron holography in the presence of additional contributions to the phase, such as those arising from changes in mean inner potential and specimen thickness.

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“…We obtained V bi values that are comparable to the Si bandgap at RT in the p/n growth sequence for both types of growth. This was unexpected, since it has also been observed that measured V bi values via EH can be up to 55% lower than expected [51]. Although these differences are known to increase for materials with larger bandgaps [28] and lower doping levels [52].…”

Section: Discussionmentioning

confidence: 83%

Abrupt degenerately-doped silicon nanowire tunnel junctions

Cordoba¹,

Teitsworth²,

Yang³

et al. 2020

Preprint

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We have confirmed the presence of narrow, degenerately-doped axial silicon nanowire (SiNW) p-n junctions via off-axis electron holography (EH). SiNWs were grown via the vaporsolid-liquid (VLS) mechanism using gold (Au) as the catalyst, silane (SiH 4 ), diborane (B 2 H 6 ) and phosphine (PH 3 ) as the precursors, and hydrochloric acid (HCl) to stabilize the growth. Two types of growth were carried out, and in each case we explored growth with both n/p and p/n sequences. In the first type, we abruptly switched the dopant precursors at the desired junction location, and in the second type we slowed the growth rate at the junction to allow the dopants to readily leave the Au catalyst. We demonstrate degenerately-doped p/n and n/p nanowire segments with abrupt potential profiles of 1.02 ± 0.02 and 0.86 ± 0.3 V, and depletion region widths as narrow as 10 ± 1 nm via EH. Low temperature current-voltage measurements show an asymmetric curvature in the forward direction that resemble planar gold-doped tunnel junctions, where the tunneling current is hidden by a large excess current. The results presented herein show that the direct VLS growth of degenerately-doped axial SiNW p-n junctions is feasible, an essential step in the fabrication of more complex SiNW-based devices for electronics and solar energy.

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Tomographic investigation of fermi level pinning at focused ion beam milled semiconductor surfaces

Cited by 25 publications

References 34 publications

Impact of electron irradiation on electron holographic potentiometry

Impact of electron irradiation on electron holographic potentiometry

Model-independent measurement of the charge density distribution along an Fe atom probe needle using off-axis electron holography without mean inner potential effects

Abrupt degenerately-doped silicon nanowire tunnel junctions

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