The adsorption of silicon on an iridium surface ruling out silicene growth

Satta, Mauro; Lacovig, Paolo; Apostol, Nicoleta G.; Dalmiglio, Matteo; Orlando, Fabrizio; Bignardi, Luca; Bana, Harsh; Travaglia, Elisabetta; Baraldi, Alessandro; Lizzit, Silvano; Larciprete, R.

doi:10.1039/c8nr00648b

Cited by 15 publications

(18 citation statements)

References 44 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…For instance, there have been numerous reports of adsorbed Si atoms diffusing through and intercalating between thin films and substrates. [28][29][30] We suspect that a similar process is at play during this deposition. In particular, we hypothesize that during Nb deposition, a few layers of Si atoms continuously float to the top surface in an effort to reduce the surface free energy of the system.…”

Section: Methodsmentioning

confidence: 80%

TOF-SIMS Analysis of Decoherence Sources in Nb Superconducting Resonators

Murthy,

Lee,

Kopas

et al. 2021

Preprint

View full text Add to dashboard Cite

Superconducting qubits have emerged as a potentially foundational platform technology for addressing complex computational problems deemed intractable with classical computing. Despite recent advances enabling multiqubit designs that exhibit coherence lifetimes on the order of hundreds of µs, material quality and interfacial structures continue to curb device performance. When niobium is deployed as the superconducting material, two-level system defects in the thin film and adjacent dielectric regions introduce stochastic noise and dissipate electromagnetic energy at the cryogenic operating temperatures. In this study, we utilize time-of-flight secondary ion mass spectrometry (TOF-SIMS) to understand the role specific fabrication procedures play in introducing such dissipation mechanisms in these complex systems. We interrogated Nb thin films and transmon qubit structures fabricated by Rigetti Computing and at the National Institute of Standards and Technology through slight variations in the processing and vacuum conditions. We find that when Nb film is sputtered onto the Si substrate, oxide and silicide regions are generated at various interfaces. We also observe that impurity species such as niobium hydrides and carbides are incorporated within the niobium layer during the subsequent lithographic patterning steps. The formation of these resistive compounds likely impact the superconducting properties of the Nb thin film. Additionally, we observe the presence of halogen species distributed throughout the patterned thin films. We conclude by hypothesizing the source of such impurities in these structures in an effort to intelligently fabricate superconducting qubits and extend coherence times moving forward.

show abstract

Section: Methodsmentioning

confidence: 80%

TOF-SIMS Analysis of Decoherence Sources in Nb Superconducting Resonators

Murthy,

Lee,

Kopas

et al. 2021

Preprint

View full text Add to dashboard Cite

show abstract

“…However, abstraction processes on graphene are known to heat locally the substrate, because of the release of the puckering energy that is left on the substrate upon H 2 molecule formation, and thus might contribute to enhance the adatom mobility. Furthermore, some surface diffusion is possible for nonthermal H adatoms that may form upon impact with graphene when the adsorption energy is efficiently channeled into translational energy along the surface, , as it may happen when light projectiles impinge on corrugated surfaces . These hot-atom species, commonly found when H interacts with bare metal surfaces, are able to travel for long distances from their formation point and can thus reach Gr defects and diffuse underneath graphene.…”

Section: Resultsmentioning

confidence: 99%

Dual-Route Hydrogenation of the Graphene/Ni Interface

et al. 2019

Self Cite

View full text Add to dashboard Cite

Nanostructured architectures based on graphene/metal interfaces might be efficiently exploited in hydrogen storage due to the attractive capability to provide adsorption sites both at the top side of graphene and at the metal substrate after intercalation. We combined in situ high resolution x-ray photoelectron spectroscopy and scanning tunneling microscopy with theoretical calculations to determine the arrangement of hydrogen atoms at the graphene/Ni(111) interface at room temperature. Our results show that at low coverage H atoms predominantly adsorb as monomers and that chemisorption saturates when ∼25% of the surface is hydrogenated. In parallel, with a much lower rate, H atoms intercalate below graphene and bind to Ni surface sites. Intercalation progressively destabilizes the C-H bonds and triggers the release of the hydrogen chemisorbed on graphene. Valence band and near edge absorption spectroscopy demonstrate that the graphene layer is fully lifted when the Ni surface is saturated with H. Thermal programmed desorption was used to determine the stability of the hydrogenated interface. Whereas the H atoms chemisorbed on graphene remain unperturbed over a wide temperature range, the intercalated phase abruptly desorbs 50-100 K above room temperature.

show abstract

“…46,47 There again, strong interactions with the substrates were demonstrated both theoretically and experimentally. 48,49 More recently, to overcome this limitation various experiments have been carried out on C-based inert substrates such as highly oriented pyrolytic graphite (HOPG) with hexagonal atomic arrangements. [50][51][52][53] On this substrate, the results demonstrated that the charge modulations caused by quantum interferences (QI) serve as templates and guide the incoming Si atoms to self-assemble in 2D clusters.…”

Section: Introductionmentioning

confidence: 99%

Van der Waals Heteroepitaxy of Air-Stable Quasi-Free-Standing Silicene Layers on CVD Epitaxial Graphene/6H-SiC

et al. 2022

View full text Add to dashboard Cite

Graphene, consisting of an inert, thermally stable material with an atomically flat, dangling bond-free surface is by essence an ideal template layer for van der Waals heteroepitaxy of two-dimensional materials such as silicene. However, depending on the synthesis method and growth parameters, graphene (Gr) substrates could exhibit, on a single sample, various surface structures, thicknesses, defects, and step heights. These structures noticeably affect the growth mode of epitaxial layers, e.g. turning the layer-by-layer growth into the Volmer Weber growth promoted by defect-assisted nucleation. In this work, the growth of silicon on chemical vapor deposited epitaxial Gr (1 ML Gr/1ML Gr buffer) on 6H-SiC(0001) substrate is investigated by a combination of atomic force microscopy (AFM), scanning tunneling microscopy (STM), x-ray photoelectron spectroscopy (XPS), scanning electron microscopy (SEM) and Raman spectroscopy measurements. It is shown that the perfect control of full-scale almost defect-free 1 ML Gr with a single surface structure and the ultra-clean conditions for molecular beam epitaxy (MBE) deposition of silicon represent key prerequisites for ensuring the growth of extended silicene sheets on epitaxial graphene. At low coverages, the deposition of Si produces large silicene sheets (some hundreds of nanometers large) attested by both AFM and SEM observations and the onset of a Raman peak at 560 cm -1 very close to the theoretical value of 570 cm -1 calculated for freestanding silicene. This vibrational mode at 560 cm -1 represents the highest ever experimentally measured value and is representative of quasi-free standing silicene with almost no interaction with inert non-metal substrates.From a coverage rate of 1ML, the silicene sheets disappear at the expense of 3D Si dendritic islands whose density, size, and thickness increase with the deposited thickness. From this coverage, the Raman mode assigned to quasi-free standing silicene totally vanishes, and the 2D flakes of silicene are no longer observed by AFM. The experimental results are in very good agreement with the results of kinetic Monte-Carlo simulations that rationalize the initial flake growth in solid-state dewetting conditions, followed by the growth of ridges surrounding and covering the 2D flakes. A full description of the growth mechanism is given. This study, which covers a wide range of growth parameters, challenges recent results stating the impossibility to grow silicene on a carbon inert surface and is very promising for large scale silicene growth. It definitely shows that silicene growth can be achieved using perfectly controlled and ultra-clean deposition conditions and an almost defect-free Gr substrate.

show abstract

The adsorption of silicon on an iridium surface ruling out silicene growth

Cited by 15 publications

References 44 publications

TOF-SIMS Analysis of Decoherence Sources in Nb Superconducting Resonators

TOF-SIMS Analysis of Decoherence Sources in Nb Superconducting Resonators

Dual-Route Hydrogenation of the Graphene/Ni Interface

Van der Waals Heteroepitaxy of Air-Stable Quasi-Free-Standing Silicene Layers on CVD Epitaxial Graphene/6H-SiC

Contact Info

Product

Resources

About