Theory of nonequilibrium single-electron dynamics in STM imaging of dangling bonds on a hydrogenated silicon surface

Livadaru, Lucian; Pitters, Jason; Taucer, Marco; Wolkow, Robert A.

doi:10.1103/physrevb.84.205416

Cited by 33 publications

(43 citation statements)

References 36 publications

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“…The DB is then analogous to the island of a single electron transistor, with the tip and substrate forming the source and drain, respectively. Exactly as for a single electron transistor, the electron occupation of the DB is then governed by the electron transfer rates on and off the DB, rather than by equilibrium with the bulk substrate17272829. Further discussion of this phenomenon, together with data illustrating the bias dependence of the depression and enhancement regions are given in Supplementary Note S1 and Supplementary Fig.…”

Section: Resultsmentioning

confidence: 99%

Quantum engineering at the silicon surface using dangling bonds

et al. 2013

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Individual atoms and ions are now routinely manipulated using scanning tunnelling microscopes or electromagnetic traps for the creation and control of artificial quantum states. For applications such as quantum information processing, the ability to introduce multiple atomic-scale defects deterministically in a semiconductor is highly desirable. Here we use a scanning tunnelling microscope to fabricate interacting chains of dangling bond defects on the hydrogen-passivated silicon (001) surface. We image both the ground-state and the excited-state probability distributions of the resulting artificial molecular orbitals, using the scanning tunnelling microscope tip bias and tip-sample separation as gates to control which states contribute to the image. Our results demonstrate that atomically precise quantum states can be fabricated on silicon, and suggest a general model of quantum-state fabrication using other chemically passivated semiconductor surfaces where single-atom depassivation can be achieved using scanning tunnelling microscopy.

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Section: Resultsmentioning

confidence: 99%

Quantum engineering at the silicon surface using dangling bonds

et al. 2013

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“…A single DB (indicated by a red arrow in figures 2(a) and (b)) appears as a bright protrusion in filled states and exhibits the characteristic dark halo surrounding it in empty states [20,22,26,34,40,45,46]. Figure 2(c) shows comparison of typical I(V) spectroscopies acquired on a single DB and the Si:H surface on the 1050°C flashed samples.…”

Section: Minimal Subsurface Dopant Depletion: 1050°c Flashed Samplesmentioning

confidence: 99%

“…The important property allowing such consideration is the DB's quantized charge state levels lying in the silicon bandgap. In fact, a DB can be either empty, singly, or doubly occupied, which corresponds, respectively, to the DB being positive(DB + ), neutral (DB 0 ), or negative(DB -) [20,22,23,26]. This makes conduction through the DB predominantly governed by tunneling rates through its charge states [22,[26][27][28], hence, the quantum dot analogy.…”

Section: Introductionmentioning

confidence: 99%

“…When probing filled states, Si Γ represents the tunneling rate from sample to DB and tip Γ that from DB to tip. The STM tip acts as a gate by locally bending the silicon bands; an important effect known as tipinduced band bending (TIBB) that was extensively studied in the case of semiconductor surfaces [26,[29][30][31][32] and was shown to play a major role in conduction through the DB in empty states [13,22,26,33,34]. In this configuration, tip Γ strongly depends on the tip-sample distance, i.e., tunnel current.…”

Section: Introductionmentioning

confidence: 99%

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Scanning tunneling spectroscopy reveals a silicon dangling bond charge state transition

et al. 2015

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We report the study of single dangling bonds (DBs) on a hydrogen-terminated silicon (100) surface using a low-temperature scanning tunneling microscope. By investigating samples prepared with different annealing temperatures, we establish the critical role of subsurface arsenic dopants on the DB electronic properties. We show that when the near-surface concentration of dopants is depleted as a result of 1250°C flash anneals, a single DB exhibits a sharp conduction step in its I(V) spectroscopy that is not due to a density of states effect but rather corresponds to a DB charge state transition. The voltage position of this transition is perfectly correlated with bias-dependent changes in the STM images of the DB at different charge states. Density functional theory calculations further highlight the role of subsurface dopants on DB properties by showing the influence of the DB-dopant distance on the DB state. We discuss possible theoretical models of electronic transport through the DB that could account for our experimental observations.

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“…5,6 Dangling bonds on hydrogen terminated surfaces have been studied extensively for their chemical reactions with organics or metals, diffusion characteristics, and creation mechanisms using scanning tunneling microscopes. 22 Therefore, when investigating the charging character of isolated or coupled DBs, it is critical to know the position of the Fermi level at the surface. [15][16][17][18] Recently, it was shown that dangling bonds on hydrogen terminated silicon surfaces should be considered as single atom quantum dots.…”

Section: Introductionmentioning

confidence: 99%

Dopant depletion in the near surface region of thermally prepared silicon (100) in UHV

Pitters

Piva

Wolkow

2012

Journal of Vacuum Science &Amp; Technology B, Nanotechnology and Microelectronics: Materials, Processing, Measurement, and Phen

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Degenerately doped (arsenic) n-type hydrogen terminated silicon (100) samples were prepared using various heat treatments for ultrahigh vacuum scanning tunneling microscopy (STM) and spectroscopy (STS) analysis. Samples heat treated to 1050 °C were found to have a consistent level of doping throughout the bulk and near surface regions. STS revealed tunneling through dopant states consistent with degenerately doped samples. SIMS profiling and HREELS measurements confirmed dopant and carrier concentrations, respectively. Samples heated to 1250 °C were found to have a reduced concentration of dopants in the near surface region. STS measurements showed shifted I/V curves and the loss of tunneling through dopant states in the band gap, indicating reduced dopant concentrations. Observations were confirmed by SIMS and HREELS where depleted dopants and reduced carrier concentrations were measured. The effect of the varying surface dopant concentrations on the STM imaging characteristics of dangling bonds on hydrogen terminated surfaces was also investigated. Understanding the effect of thermal processing on near surface dopant atom concentrations will permit better control over equilibrium charge occupation and charging characteristics of dangling bond midgap states on H:silicon.

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Theory of nonequilibrium single-electron dynamics in STM imaging of dangling bonds on a hydrogenated silicon surface

Cited by 33 publications

References 36 publications

Quantum engineering at the silicon surface using dangling bonds

Quantum engineering at the silicon surface using dangling bonds

Scanning tunneling spectroscopy reveals a silicon dangling bond charge state transition

Dopant depletion in the near surface region of thermally prepared silicon (100) in UHV

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