Optimizing dopant activation in Si:P double <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" altimg="si0014.gif" overflow="scroll"><mml:mi mathvariant="normal">δ</mml:mi><mml:mtext>-layers</mml:mtext></mml:math>

McKibbin, Sarah R.; Clarke, W.A.; Fuhrer, Andreas; Simmons, M. Y.

doi:10.1016/j.jcrysgro.2010.08.003

Cited by 15 publications

(7 citation statements)

References 22 publications

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“…In the direction normal to the dopant plane, the δ-layer is separated from its periodic images by 40 atomic layers, which affords an adequate degree of electronic separation. In the in-plane direction a (4 × 4) unit cell of 16 atoms (with 4 P and 12 Si in the δ-layer representing the measured 2.4 × 10 14 cm –2 dopant density) is used. The use of a (4 × 4) unit cell necessitates a subsequent unfolding of the calculated band minima to their position in the (1 × 1) Brillouin zone that is probed in experiment.…”

Section: Methodsmentioning

confidence: 99%

“…The experimentally determined value is centrally placed within the range of reported calculated values; 6 to 270 meV. − This wide range of values arises because the calculated valley splitting is sensitive to the arrangement of dopants in the δ-layer, , as well as to other physical parameters such as dopant density, the confinement potential (related to dopant segregation), and to the particular calculational approach used. The preparation recipe used here is known to reliably produce a dense (2.4 × 10 14 cm –2 ) and narrow (<1 nm wide) dopant profile , that can be well represented in the calculations. The lack of periodicity in the δ-layer states, after removing the surface Umklapp process (Figure b), supports the notion of a dopant layer that lacks long-range order, but does not exclude the likely possibility of local ordering. , We therefore primarily attribute the discrepancy between the measured and calculated valley splitting values to an ill-defined dopant arrangement in the δ-layer.…”

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confidence: 99%

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Valley Splitting in a Silicon Quantum Device Platform

Miwa

Warschkow

Carter³

et al. 2014

Nano Lett.

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By suppressing an undesirable surface Umklapp process, it is possible to resolve the two most occupied states (1Γ and 2Γ) in a buried two-dimensional electron gas (2DEG) in silicon. The 2DEG exists because of an atomically sharp profile of phosphorus dopants which have been formed beneath the Si(001) surface (a δ-layer). The energy separation, or valley splitting, of the two most occupied bands has critical implications for the properties of δ-layer derived devices, yet until now, has not been directly measurable. Density functional theory (DFT) allows the 2DEG band structure to be calculated, but without experimental verification the size of the valley splitting has been unclear. Using a combination of direct spectroscopic measurements and DFT we show that the measured band structure is in good qualitative agreement with calculations and reveal a valley splitting of 132 ± 5 meV. We also report the effective mass and occupation of the 2DEG states and compare the dispersions and Fermi surface with DFT.

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Section: Methodsmentioning

confidence: 99%

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confidence: 99%

Valley Splitting in a Silicon Quantum Device Platform

Miwa

Warschkow

Carter³

et al. 2014

Nano Lett.

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“…To circumvent this problem, and thus to increase the total amount of donors, here we propose to stack several δ layers separated by a thin Ge spacer of high crystalline and morphological quality. The stacking of multiple ALD layers has proven to be difficult in both Si [12] and Ge [13]. This is mainly due to the need for preserving the precision of a single ALD layer while maintaining an atomically flat surface of the encapsulation layer which will act, in turn, as the substrate for the subsequent layer of the ALD stack.…”

Section: (Some Figures In This Article Are In Colour Only In the Elec...mentioning

confidence: 99%

Phosphorus atomic layer doping of germanium by the stacking of multiple δ layers

et al. 2011

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In this paper we demonstrate the fabrication of multiple, narrow, and closely spaced δ-doped P layers in Ge. The P profiles are obtained by repeated phosphine adsorption onto atomically flat Ge(001) surfaces and subsequent thermal incorporation of P into the lattice. A dual-temperature epitaxial Ge overgrowth separates the layers, minimizing dopant redistribution and guaranteeing an atomically flat starting surface for each doping cycle. This technique allows P atomic layer doping in Ge and can be scaled up to an arbitrary number of doped layers maintaining atomic level control of the interface. Low sheet resistivities (280 Ω/ [symbol see text ) and high carrier densities (2 × 10(14) cm( - 2), corresponding to 7.4 × 10(19) cm( - 3)) are demonstrated at 4.2 K.

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“…The electron mobility in CVD graphene [ 32 ] can be within the range 800–16000 cm 2 V −1 s −1 (although higher mobilities have been found with suspended exfoliated graphene, [ 32 ] the upper limit is far smaller when incorporated into a device), whereas with Si:P δ‐layers μ ≈ 100 cm 2 V −1 s −1 . [ 34 ] The electron density of graphene [ 35 ] is limited to approximately two orders of magnitude lower than maximally doped Si:P δ‐layers, for which [ 36 ] n 2D ≈ 1 × 10 14 cm −2 . Additionally, the kinetic inductance must be considered for low dimension, high mobility transmission lines, as dominance of the inductance can induce parasitic plasmonics resonances.…”

Section: Introductionmentioning

confidence: 99%

Microwave Properties of 2D CMOS Compatible Co‐Planar Waveguides Made from Phosphorus Dopant Monolayers in Silicon

Chapman

Votsi

Stock

et al. 2022

Adv Elect Materials

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Low‐dimensional microwave interconnects have important applications for nanoscale electronics, from complementary metal–oxide‐semiconductor (CMOS) to silicon quantum technologies. Graphene is naturally nanoscale and has already demonstrated attractive electronic properties, however its application to electronics is limited by available fabrication techniques and CMOS incompatibility. Here, the characteristics of transmission lines made from silicon doped with phosphorus are investigated using phosphine monolayer doping. S‐parameter measurements are performed between 4–26 GHz from room temperature down to 4.5 K. At 20 GHz, the measured monolayer transmission line characteristics consist of an attenuation constant of 40 dB mm−1 and a characteristic impedance of 600 Ω. The results indicate that Si:P monolayers are a viable candidate for microwave transmission and that they have a.c. properties similar to graphene, with the additional benefit of extremely precise, reliable, stable, and inherently CMOS compatible fabrication.

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Optimizing dopant activation in Si:P double δ-layers

Cited by 15 publications

References 22 publications

Valley Splitting in a Silicon Quantum Device Platform

Valley Splitting in a Silicon Quantum Device Platform

Phosphorus atomic layer doping of germanium by the stacking of multiple δ layers

Microwave Properties of 2D CMOS Compatible Co‐Planar Waveguides Made from Phosphorus Dopant Monolayers in Silicon

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