Epitaxial top-gated atomic-scale silicon wire in a three-dimensional architecture

McKibbin, Sarah R.; Scappucci, Giordano; Pok, W.; Simmons, M. Y.

doi:10.1088/0957-4484/24/4/045303

Cited by 31 publications

(28 citation statements)

References 37 publications

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“…A rather unique branch of the 2D material family are ultrashallow, high-density, doping profiles in semiconductors, so-called δ-layers. In particular, phosphorus δ-layers in silicon (Si:P δ-layers) combined with atomically precise lithography have led to recent technological successes towards scalable qubit architectures [5][6][7][8]. It has been demonstrated that P donors, which can act as qubits, in Si have long spin lifetimes [9,10] which are essential for spin-based quantum calculations.…”

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confidence: 99%

Simultaneous Conduction and Valence Band Quantization in Ultrashallow High-Density Doping Profiles in Semiconductors

et al. 2018

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We demonstrate simultaneous quantisation of conduction band (CB) and valence band (VB) states in silicon using ultra-shallow, high density, phosphorus doping profiles (so-called Si:P δ-layers). We show that, in addition to the well known quantisation of CB states within the dopant plane, the confinement of VB-derived states between the sub-surface P dopant layer and the Si surface gives rise to a simultaneous quantisation of VB states in this narrow region. We also show that the VB quantisation can be explained using a simple particle-in-a-box model, and that the number and energy separation of the quantised VB states depend on the depth of the P dopant layer beneath the Si surface. Since the quantised CB states do not show a strong dependence on the dopant depth (but rather on the dopant density), it is straightforward to exhibit control over the properties of the quantised CB and VB states independently of each other by choosing the dopant density and depth accordingly, thus offering new possibilities for engineering quantum matter.There has been a surge of interest in two-dimensional (2D) materials due to their remarkable quantum properties. Graphene and layered transition metal dichalcogenides are just two examples of such materials that have been recently studied and proffered as advantageous for developing quantum electronic devices [1][2][3][4]. A rather unique branch of the 2D material family are ultrashallow, high-density, doping profiles in semiconductors, so-called δ-layers. In particular, phosphorus δ-layers in silicon (Si:P δ-layers) combined with atomically precise lithography have led to recent technological successes towards scalable qubit architectures [5][6][7][8]. It has been demonstrated that P donors, which can act as qubits, in Si have long spin lifetimes [9,10] which are essential for spin-based quantum calculations. Importantly, Si:P δ-layers can be readily synthesized -they are comprised of a Si(001) substrate with a high density P dopant profile situated a few nanometers beneath an epitaxial grown Si encapsulation layer -and they are potentially straightforward to integrate into existing Si-based technology. Both the dopant layer and the encapsulation layer can be easily modified during the growth process [11][12][13], and it is this flexibility that makes δ-layers so promising, not only for enhancing the performance of quantum electronic devices, but for engineering new 2D materials with new capabilities.The confinement of a high density, atomically thin layer of P atoms beneath the surface abruptly changes the potential within the Si crystal. This brings about strong bending of the conduction band (CB) and valence band (VB) around the dopant plane, leading to strong confinement of the silicon CB. This strong confinement results in lowering and discretisation of the CB and consequently gives the system metallic character [14][15][16][17][18]. These CB states have been studied in considerable detail [16,[19][20][21], and it has been determined that their binding energy and energy separa...

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confidence: 99%

Simultaneous Conduction and Valence Band Quantization in Ultrashallow High-Density Doping Profiles in Semiconductors

et al. 2018

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“…It is essential that this encapsulation layer be crystalline in order to achieve optimum dopant activation and carrier densities. Furthermore, high quality low temperature Si overgrowth not only improves the performance of 2D patterned devices, but also plays an important role in extended applications involving 3D architectures [2],[36],[37] .…”

Section: Resultsmentioning

confidence: 99%

“…Recent advances in atomic scale patterning of phosphorus dopants on hydrogen terminated Si (100) surfaces using STM lithography have resulted in a variety of atomic scale devices, including wires [1],[2] , quantum dots [3],[4] and single atom transistors [5] . As the building blocks for the Si based Kane quantum computer [6],[7],[8] , most of these approaches rely on patterning a hydrogen resist layer [9],[10] and selectively adsorbing dopant atoms in areas defined by lithographic patterns [11],[12] .…”

Section: Introductionmentioning

confidence: 99%

Silicon epitaxy on H-terminated Si (100) surfaces at 250 °C

Xiao

Namboodiri

et al. 2016

Applied Surface Science

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Low temperature Si epitaxy has become increasingly important due to its critical role in the encapsulation and performance of buried nanoscale dopant devices. We demonstrate epitaxial growth up to nominally 25 nm, at 250°C, with analysis at successive growth steps using STM and cross section TEM to reveal the nature and quality of the epitaxial growth. STM images indicate that growth morphology of both Si on Si and Si on H-terminated Si (H: Si) is epitaxial in nature at temperatures as low as 250 °C. For Si on Si growth at 250 °C, we show that the Si epitaxial growth front maintains a constant morphology after reaching a specific thickness threshold. Although the in-plane mobility of silicon is affected on the H: Si surface due to the presence of H atoms during initial sub-monolayer growth, STM images reveal long range order and demonstrate that growth proceeds by epitaxial island growth albeit with noticeable surface roughening.

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“…Nanosilicon may also acquire quantum mechanical properties at small quantum dot sizes [42,164,166,167], a feature that may help account for certain other observations in the homeopathic drug development research literature [147,148,168]. Doping of the nanosilicon and nanosilica by the medicine source material and other trace contaminants in solution during early preparation steps [9] may add more memory and amplification mechanisms [164,169,170].…”

Section: Stochastic Resonance Peakmentioning

confidence: 99%

Nonlinear Response Amplification Mechanisms for Low Doses of Natural Product Nanomedicines: Dynamical Interactions with the Recipient Complex Adaptive System

Bell

Sarter

Koithan

et al. 2013

J Nanomed Nanotechol

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The purpose of the present paper is (a) to outline the self-organized, complex adaptive network nature of the organism as recipient of nanomedicines; (b) to propose several nonlinear endogenous amplification processes by which pulsed low doses of traditional, homeopathically-manufactured natural product nanomedicines may stimulate a return toward healthier function; and (c) to discuss their potential relevance to novel, but safer than conventional dosing strategies for contemporary nanomedicines. Homeopathy is an over 200-year-old system of complementary and alternative medicine (CAM) that uses low doses of natural plant-, mineral-, and animal-sourced nanomedicines. Homeopathic manufacturing is "green", with mechanical grinding in lactose and agitation in ethanol-water as primary reagents. Agitation within glass containers at room temperature may also contribute nanosilica and nanosilicon as drug delivery vehicles and biological amplifiers. The medicine selection is matched to the recipient organism's systemic patterns of dysfunction and pulsed in the timing of the discrete doses. Endogenous amplification processes within the recipient organism may involve hormesis, time-dependent sensitization, and/or stochastic resonance. Effects are adaptive and systemically diffuse, i.e., causally indirect, rather than pharmacological and local, i.e., direct. All of these nonlinear response processes require interaction of the nanoparticle (NP) dose with the organism as a complex adaptive system. The pulsed NP dose serves as a low intensity salient danger signal for the organism to make network-wide adaptive changes that can lead to healing. The historically safe therapeutic approach of homeopathic nanomedicine dosing avoids risks of high, continuous doses and cumulative toxicity that contemporary nanomedicine researchers are now trying to solve while using NPs as if they were conventional bulk drugs. Integrating the insights, technical procedures, and clinical dosing approaches from modern and homeopathic nanomedicine could lead to major advances in the field for more effective and safer translational applications.NPs in homeopathic medicines [3]. NP concentrations are low, but measurable [3]. Like modern manufactured NPs [13], homeopathicallymanufactured medicines in solution also can exhibit aging effects [9,14]. These nanomedicines are delivered either in ethanolic liquids or sprayed and dried onto lactose or lactose/sucrose pellets for oral administration.Homeopathic manufacturing materials and methods are inherently "green" [15,16]. Previous papers have addressed the striking similarities between modern top-down mechanical attrition procedures for making nanoparticles (NPs) [17] and historical homeopathic medicine manufacturing methods and materials [15,[18][19][20][21]. These similarities include mechanically grinding source materials in lactose for hours and repeatedly agitating ethanol-water solutions containing the source Citation: Bell IR, Sarter B, Koithan M, Standish LJ, Banerji P, et al. (2013) Nonlinea...

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Epitaxial top-gated atomic-scale silicon wire in a three-dimensional architecture

Cited by 31 publications

References 37 publications

Simultaneous Conduction and Valence Band Quantization in Ultrashallow High-Density Doping Profiles in Semiconductors

Simultaneous Conduction and Valence Band Quantization in Ultrashallow High-Density Doping Profiles in Semiconductors

Silicon epitaxy on H-terminated Si (100) surfaces at 250 °C

Nonlinear Response Amplification Mechanisms for Low Doses of Natural Product Nanomedicines: Dynamical Interactions with the Recipient Complex Adaptive System

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