Carrier control in 2D transition metal dichalcogenides with Al2O3 dielectric

Lau, Chit Siong; Chee, Jing Yee; Thian, Dickson; Kawai, Hiroyo; Deng, Jie; Wong, Swee Liang; Ooi, Zi En; Lim, Yee‐Fun; Goh, Kuan Eng Johnson

doi:10.1038/s41598-019-45392-9

Cited by 13 publications

(13 citation statements)

References 28 publications

(36 reference statements)

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“…Since 2015, there has been several report toward the development of valleytronic devices [ 92 ] and spin‐valley qubits based on TMDCs. [ 34–40,54,83 ] The strategy is to employ electrostatic gating to form quantum dots and realize a scalable TMDC based qubit platform, relying on the concepts espoused in the theoretical proposals of Figure 7. These reports demonstrate the ability to electrostatically gate a range of 2D TMDC materials to achieve carrier confinement.…”

Section: Tmdc‐based Qubitsmentioning

confidence: 99%

“…in studies of dual‐gated few‐layer exfoliated MoS 2 and WSe 2 as shown in Figure . [ 39 ] While transport through the TMDC film could be independently pinched off by split top gates, the current shows only a single current step in contrast to the expected multiple regularly spaced steps seen in higher quality hBN encapsulated devices. [ 34,35 ] Our experiments on top‐gated CVD monolayer MoS 2 films with HfO 2 dielectric likewise show strong disorder‐defined tunnel couplings with Coulomb oscillations that are dominated by a single gate (Figure 9e,f), similar to observations by Wang et al.…”

Section: Tmdc‐based Qubitsmentioning

confidence: 99%

“…[ 32,33 ] Hence, the 2D TMDC family is a very compelling alternative for building solid‐state qubits. Various groups [ 31,34–40 ] have therefore invested efforts (see for example the facilities highlighted in Figure ) to build electrostatically gated quantum dots in 2D TMDCs which could potentially lead to the development of qubits on the same platform. This report provides an update of the progress in this field.…”

Section: Introductionmentioning

confidence: 99%

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Toward Valley‐Coupled Spin Qubits

et al. 2020

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The bid for scalable physical qubits has attracted many possible candidate platforms. In particular, spin‐based qubits in solid‐state form factors are attractive as they could potentially benefit from processes similar to those used for conventional semiconductor processing. However, material control is a significant challenge for solid‐state spin qubits as residual spins from substrate, dielectric, electrodes, or contaminants from processing contribute to spin decoherence. In the recent decade, valleytronics has seen a revival due to the discovery of valley‐coupled spins in monolayer transition metal dichalcogenides. Such valley‐coupled spins are protected by inversion asymmetry and time reversal symmetry and are promising candidates for robust qubits. In this report, the progress toward building such qubits is presented. Following an introduction to the key attractions in fabricating such qubits, an up‐to‐date brief is provided for the status of each key step, highlighting advancements made and/or outstanding work to be done. This report concludes with a perspective on future development highlighting major remaining milestones toward scalable spin‐valley qubits.

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Section: Tmdc‐based Qubitsmentioning

confidence: 99%

Section: Tmdc‐based Qubitsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Toward Valley‐Coupled Spin Qubits

et al. 2020

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“…[ 14,15,28,29 ] Furthermore, realizing gated TMDC quantum dot devices is essential for quantum computation applications with tunable electrical control while minimizing undesirable edge states from physical etching, and requires suitable dielectrics for effective carrier confinement at nanoscale dimensions. [ 30–35 ]…”

Section: Introductionmentioning

confidence: 99%

Gate‐Defined Quantum Confinement in CVD 2D WS₂

et al. 2021

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metal-oxide-semiconductor field-effect transistors (MOSFETs). As we continue to squeeze the last few drops from the lemon that is Moore's law, alternative channel materials other than silicon will be needed for future devices. [2] Likewise, replacement of traditional dielectrics, silicon oxide, with high-k dielectrics are being implemented for increased gate capacitance with low leakage currents. Currently, state-of-the-art MOSFETs manufactured by Intel utilizes a 2.6 nm thick high-k HfO 2 gate dielectric in their 14-nm FinFET structures. [3] For channel materials, promising candidates are 2D semiconductors such as transition metal dichalcogenides (TMDCs). [4][5][6][7][8][9][10] 2D TMDCs are an important class of atomically thin materials with novel properties such as tunable layer-dependent direct bandgaps, strong photoluminescence, large spin-orbit coupling, and unique spin-valley coupling. [11][12][13][14][15] These exceptional properties are attractive for applications in electronics, optoelectronic and quantum information processing. 2D TMDCs were first isolated with the "Scotch tape" technique, where adhesive tapes "peel" thin flakes from bulk crystals that are then repeatedly exfoliated to a single atomic layer. [16] Devices are fabricated through manual assembly and stacking of such semiconducting or insulating micron Temperature-dependent transport measurements are performed on the same set of chemical vapor deposition (CVD)-grown WS 2 single-and bilayer devices before and after atomic layer deposition (ALD) of HfO 2 . This isolates the influence of HfO 2 deposition on low-temperature carrier transport and shows that carrier mobility is not charge impurity limited as commonly thought, but due to another important but commonly overlooked factor: interface roughness. This finding is corroborated by circular dichroic photoluminescence spectroscopy, X-ray photoemission spectroscopy, cross-sectional scanning transmission electron microscopy, carrier-transport modeling, and density functional modeling. Finally, electrostatic gate-defined quantum confinement is demonstrated using a scalable approach of large-area CVD-grown bilayer WS 2 and ALD-grown HfO 2 . The high dielectric constant and low leakage current enabled by HfO 2 allows an estimated quantum dot size as small as 58 nm. The ability to lithographically define increasingly smaller devices is especially important for transition metal dichalcogenides due to their large effective masses, and should pave the way toward their use in quantum information processing applications.The ORCID identification number(s) for the author(s) of this article can be found under https://doi.org/10.1002/adma.202103907.

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“…It is known that for carriers that are spatially localized the valley degree of freedom is still well defined. There are many theoretical 17,[53][54][55][56][57][58][59][60][61][62][63][64] and experimental 51,[65][66][67][68][69] studies of quantum dots (QDs) based on MoS 2 and related TMDCs pointing towards promising routes to various spin-valley massive-Dirac-fermion-based qubit realizations, as summarized recently in Ref. [70].…”

Section: Introductionmentioning

confidence: 99%

Valley two-qubit system in a MoS$_2$-monolayer gated double quantum dot

Pawłowski,

Bieniek,

Woźniak

2021

Preprint

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We explore a two-qubit system defined on valley isospins of two electrons confined in a gate-defined double quantum dot created within a MoS2 monolayer flake. We show how to initialize, control, interact and read out such valley qubits only by electrical means using voltages applied to the local planar gates, which are layered on the top of the flake. By demonstrating the two-qubit exchange or readout via the Pauli blockade, we prove that valley qubits in transition-metal-dichalcogenide semiconductors family fulfill the universality criteria and represent a scalable quantum computing platform. Our numerical experiments are based on the tight-binding model for a MoS2 monolayer, which gives single-electron eigenstates that are then used to construct a basis of Slater-determinants for the two-electron configuration space. We express screened electron-electron interactions in this basis by calculating the Coulomb matrix elements using localized Slater-type orbitals. Then we solve the time-dependent Schrödinger equation and obtain an exact time-evolution of the two-electron system. During the evolution we simultaneously solve the Poison equation, finding the confinement potential controlled via voltages applied to the gates.

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Carrier control in 2D transition metal dichalcogenides with Al2O3 dielectric

Cited by 13 publications

References 28 publications

Toward Valley‐Coupled Spin Qubits

Toward Valley‐Coupled Spin Qubits

Gate‐Defined Quantum Confinement in CVD 2D WS₂

Valley two-qubit system in a MoS$_2$-monolayer gated double quantum dot

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Carrier control in 2D transition metal dichalcogenides with Al2O3 dielectric

Cited by 13 publications

References 28 publications

Toward Valley‐Coupled Spin Qubits

Toward Valley‐Coupled Spin Qubits

Gate‐Defined Quantum Confinement in CVD 2D WS2

Valley two-qubit system in a MoS$_2$-monolayer gated double quantum dot

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Product

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Gate‐Defined Quantum Confinement in CVD 2D WS₂