Lithography and doping in strained Si towards atomically precise device fabrication

Lee, W C T; McKibbin, Sarah R.; Thompson, D.L.; Xue, Kaiping; Scappucci, Giordano; Bishop, Nathaniel; Celler, G. K.; Carroll, Malcolm S.; Simmons, M. Y.

doi:10.1088/0957-4484/25/14/145302

Cited by 12 publications

(10 citation statements)

References 37 publications

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“…Additionally strain can drastically reduce valley oscillations of exchange coupling [18,19], which would play an important role in field control of qubits in strained environments. Recent progress towards atomically precise fabrication of donors in strained Si provides a testbed to demonstrate the advantages of strain in the realization of donor-based qubit devices [20]. Whilst the previous studies have exclusively considered strain or electric field effects on the quantum control of the donors, it is clear that through valley physics there is a subtle interplay between these two effects.…”

Section: Introductionmentioning

confidence: 99%

Strain and electric field control of hyperfine interactions for donor spin qubits in silicon

et al. 2015

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Control of hyperfine interactions is a fundamental requirement for quantum computing architecture schemes based on shallow donors in silicon. However, at present, there is lacking an atomistic approach including critical effects of central-cell corrections and non-static screening of the donor potential capable of describing the hyperfine interaction in the presence of both strain and electric fields in realistically sized devices. We establish and apply a theoretical framework, based on atomistic tight-binding theory, to quantitatively determine the strain and electric field dependent hyperfine couplings of donors. Our method is scalable to millions of atoms, and yet captures the strain effects with an accuracy level of DFT method. Excellent agreement with the available experimental data sets allow reliable investigation of the design space of multi-qubit architectures, based on both strain-only as well as hybrid (strain+field) control of qubits. The benefits of strain are uncovered by demonstrating that a hybrid control of qubits based on (001) compressive strain and in-plane (100 or 010) fields results in higher gate fidelities and/or faster gate operations, for all of the four donor species considered (P, As, Sb, and Bi). The comparison between different donor species in strained environments further highlights the trends of hyperfine shifts, providing predictions where no experimental data exists. Whilst faster gate operations are realisable with in-plane fields for P, As, and Sb donors, only for the Bi donor, our calculations predict faster gate response in the presence of both in-plane and out-of-plane fields, truly benefiting from the proposed planar field control mechanism of the hyperfine interactions.

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Section: Introductionmentioning

confidence: 99%

Strain and electric field control of hyperfine interactions for donor spin qubits in silicon

et al. 2015

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“…Normally for such devices, this in-situ preparation starts with a 10 h-anneal at 600 • C followed by a hightemperature flash annealing (typically above 1050 • C) to remove the native oxide 25 . However, this high temperature anneal cannot be performed here with a thin strained layer because it results in cross-hatching due to the strain variation across the wafer, which is notably unsuitable for STM lithography 33 . This high-temperature flash also incurs a high risk of dewetting the thin strained layer.…”

Section: Sample Fabrication and Structural Analysismentioning

confidence: 99%

Valley population of donor states in highly strained silicon

B.¹,

Ng²,

Salfi³

et al. 2021

Preprint

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Strain is extensively used to controllably tailor the electronic properties of materials. In the context of indirect band-gap semiconductors such as silicon, strain lifts the valley degeneracy of the six conduction band minima, and by extension the valley states of electrons bound to phosphorus donors. Here, single phosphorus atoms are embedded in an engineered thin layer of silicon strained to 0.8% and their wave function imaged using spatially resolved spectroscopy. A prevalence of the outof-plane valleys is confirmed from the real-space images, and a combination of theoretical modelling tools is used to assess how this valley repopulation effect can yield isotropic exchange and tunnel interactions in the xy-plane relevant for atomically precise donor qubit devices. Finally, the residual presence of in-plane valleys is evidenced by a Fourier analysis of both experimental and theoretical images, and atomistic calculations highlight the importance of higher orbital excited states to obtain a precise relationship between valley population and strain. Controlling the valley degree of freedom in engineered strained epilayers provides a new competitive asset for the development of donor-based quantum technologies in silicon.

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“…In other words -by means of deterministic doping, e.g. using either ion implantation (SII) [29] or so called STM-Lithography [30].…”

Section: Future Stepsmentioning

confidence: 99%

Dopant-Based Charge Sensing Utilizing P-I-N Nanojunction

Nowak

Jabłoński

2017

Metrology and Measurement Systems

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We studied lateral silicon p-i-n junctions, doped with phosphorus and boron, regarding charge sensing feasibility. In order to examine the detection capabilities and underlying mechanism, we used in a complementary way two measurement techniques. First, we employed a semiconductor parameter analyzer to measure I−V characteristics at a low temperature, for reverse and forward bias conditions. In both regimes, we systematically detected Random Telegraph Signal. Secondly, using a Low Temperature Kelvin Probe Force Microscope, we measured surface electronic potentials. Both p-i-n junction interfaces, p-i and i-n, were observed as regions of a dynamic behaviour, with characteristic time-dependent electronic potential fluctuations. Those fluctuations are due to single charge capture/emission events. We found analytically that the obtained data could be explained by a model of twodimensional p-n junction and phosphorus-boron interaction at the edge of depletion region. The results of complementary measurements and analysis presented in this research, supported also by the previous reports, provide fundamental insight into the charge sensing mechanism utilizing emergence of individual dopants.

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Lithography and doping in strained Si towards atomically precise device fabrication

Cited by 12 publications

References 37 publications

Strain and electric field control of hyperfine interactions for donor spin qubits in silicon

Strain and electric field control of hyperfine interactions for donor spin qubits in silicon

Valley population of donor states in highly strained silicon

Dopant-Based Charge Sensing Utilizing P-I-N Nanojunction

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