Charge State Control and Relaxation in an Atomically Doped Silicon Device

Andresen, S. E.; Brenner, R.; Wellard, Cameron; Yang, C. H.; Hopf, T.; Escott, Christopher C.; Clark, Robert G.; Dzurak, A. S.; Jamieson, David N.; Hollenberg, Lloyd C. L.

doi:10.1021/nl070797t

Cited by 59 publications

(54 citation statements)

References 26 publications

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“…Finally, we point out that the spin-dependent tunneling demonstrated in this paper is analogous to the mechanism proposed by Kane for readout of solid state donor qubits 3 . Whilst previous attempts to investigate this mechanism have relied on remote charge detection of the transfer of an electron between clusters of donors 20 and even two single donors 21 , this work demon-strates a spin dependent electronic tunneling transitions between localized defect sites. Note that the 31 P−P b mechanism that dominates at low magnetic fields does not demonstrate this effect, as energy in not conserved.…”

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Spin-dependent processes at the crystallineSi-SiO2interface at high magnetic fields

et al. 2008

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An experimental study on the nature of spin-dependent excess charge carrier transitions at the interface between (111) oriented phosphorous doped ([P]≈ 10 15 cm −3 ) crystalline silicon and silicon dioxide at high magnetic field (B 0 ≈ 8.5T) is presented. Electrically detected magnetic resonance (EDMR) spectra of the hyperfine split 31 P donor electron transitions and paramagnetic interface defects were conducted at temperatures in the range 3 K≤ T ≤12 K. The results at these previously unattained (for EDMR) magnetic field strengths reveal the dominance of spin-dependent processes that differ from the previously well investigated recombination between the 31 P donor and the P b state, which dominates at low magnetic fields. While magnetic resonant current responses due to 31 P and P b states are still present, they do not correlate and only the P b contribution can be associated with an interface process due to spin-dependent tunneling between energetically and physically adjacent P b states. This work provides an experimental demonstration of spin-dependent tunneling between physically adjacent and identical electronic states as proposed by Kane for readout of donor qubits. 71.55.Cn, 73.40.Qv Phosphorus doped crystalline silicon (c-Si:P) is one of the most widely utilized semiconductor materials, with applications ranging from conventional microelectronics 1 to proposed and presently widely investigated concepts for spintronics 2 and spin-based quantum information processing (QIP) 3 . Silicon based spin-QIP and spintronics concepts aim to utilize the comparatively weak spin-orbit coupling present in this material, and the correspondingly very long spincoherence times 2,3 , as well as the impact of spin-selection rules on electronic transitions which can be used for spin readout 4 . Most of these applications involve electrical transport and spin manipulation at or near the silicon-silicon dioxide (SiO 2 ) interface, making the understanding of spin processes in this region extremely important. Numerous studies of spin-dependent transport and recombination at the interface between c-Si:P and SiO 2 have recently been undertaken, with the aim of identifying and understanding these mechanisms 5,6,7 , and showing that they can be utilized for the observation of very small ensembles of donors 8 and coherent spin motion 7,9 . Additionally, spin dependent transport in two dimensional electron gases at the c-Si/SiO 2 interface has been demonstrated 10,11 . However, no systematic study of such processes at high magnetic field has been conducted to date, with the only data at magnetic fields B 0 > 400 mT given by a single electrically detected magnetic resonance (EDMR) spectrum recorded at B 0 = 7.1 T and a temperature T = 4 K 12 .In the following, a systematic investigation of the spin dependent processes at the interface between c-Si:P and SiO 2 are presented for high magnetic fields (B 0 ≈ 8.5 T) at temperatures in the range 3 K≤ T ≤12 K.We show that the dominant spin-dependent recombination mechanism at low magnet...

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Spin-dependent processes at the crystallineSi-SiO2interface at high magnetic fields

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“…In our sample, Si donors reside in Al 0.3 Ga 0. 7 As, for which a * 0 = 7.3 nm and Ry * = 8.1 meV (ref. 19).…”

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Scanning-probe spectroscopy of semiconductor donor molecules

et al. 2008

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Semiconductor devices continue to press into the nanoscale regime, and new applications have been proposed for which a single dopant atom acts as the functional part of the device 1-3 . Moreover, because shallow donors and acceptors are analogous to hydrogen atoms, experiments on small numbers of dopants have the potential to be a testing ground for fundamental questions of atomic and molecular physics 4,5 . Although dopant properties are well understood with respect to the bulk, the study of configurations of dopants in small numbers is an emerging field 6,7 . Here we present local capacitance measurements of electrons entering silicon donors in a gallium arsenide heterostructure. To the best of our knowledge, this study is the first example of single-electron capacitance spectroscopy carried out directly with a scanning probe tip 8 . The precise position with respect to tip voltage of the observed single-electron peaks varies with the location of the probe, reflecting a random distribution of silicon within the donor plane. In addition, three broad capacitance peaks are observed independent of the probe location, indicating clusters of electrons entering the system at approximately the same voltages. These broad peaks are consistent with the addition energy spectrum of donor molecules, effectively formed by nearest-neighbour pairs of silicon donors.Electron tunnelling spectroscopy through isolated dopants has been observed in transport studies 9,10 . In addition, Geim and coworkers identified resonances due to two closely spaced donors, effectively forming donor molecules 11 . Rather than measuring transport current, our scanning-probe method is essentially a capacitance technique 8,12 . In contrast to the work of Geim et al., the measurements show discernible peaks attributed to successive electrons entering the molecules.Our method is an extension of scanning charge accumulation imaging 12 . Figure 1a shows the experiment schematically. The key component is a metallic tip with an apex of radius ∼ 50 nm, connected directly to a charge sensor, which achieves a sensitivity of 0.01e/ √ H z (ref. 13). For the capacitance spectroscopy measurements reported here, the tip's position is fixed (that is, not scanned) at a distance of ∼1 nm from the sample surface. We then monitor the tip's a.c. charge q tip in response to an a.c. excitation voltage V exc applied to an underlying electrode, as a function of d.c. bias voltage V tip . As detailed in the Methods section, if the quantum system below the tip can accommodate additional charge, the excitation voltage causes it to resonate between the system and the underlying electrode-giving rise to an enhanced capacitance,The first observations of donor-layer capacitance peaks acquired with our method probed a gallium arsenide heterostructure sample grown by molecular beam epitaxy, for which the donor layer was bulk-doped with Si at a density of 10 24 m −3 . To achieve better characterized results that would be more conducive to analysis, we used a GaAs [001] heterostructure...

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“…The ability to manipulate and probe small numbers of dopant atoms in semiconductors represents an emerging line of research, motivated by the continued miniaturization of semiconductor devices and potential applications where the dopants themselves form the functional part of a device [1][2][3][4][5]. Although donor properties are well understood with respect to bulk semiconductors, new questions arise in nanosystems such as the interaction between the donor confinement potential and the potential applied by nearby nanometer-scale electrodes.…”

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Scanning Probe Microscopy

2013

Materials Characterization

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a b s t r a c tWe review recently reported scanned-probe capacitance measurements of electrons entering silicon donors in a gallium-arsenide heterostructure. Single-electron peaks were observed in the capacitanceversus-voltage curves. The precise voltage position of the peaks varied with the location of the probe, reflecting a random distribution of silicon within the donor plane. In addition, three broader capacitance peaks were observed independent of the probe location, indicating clusters of electrons entering the system at approximately the same voltages. These broad peaks are consistent with the addition energy spectrum of donor molecules, effectively formed by nearest-neighbor pairs of silicon donors.

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Charge State Control and Relaxation in an Atomically Doped Silicon Device

Cited by 59 publications

References 26 publications

Spin-dependent processes at the crystallineSi-SiO2interface at high magnetic fields

Spin-dependent processes at the crystallineSi-SiO2interface at high magnetic fields

Scanning-probe spectroscopy of semiconductor donor molecules

Scanning Probe Microscopy

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