Replacing Doping in Nano-Silicon: Ultimate Miniaturization, Energy Efficiency, and Cryo-Functionality.

Hard entropy limits of impurity doping prevent further miniaturization of low nanoscale silicon-based very large scale integration (VLSI) devices, thereby obstructing the path toward more energy-efficient VLSI designs with higher yield in compute power. As demonstrated here by synchrotron UV photoelectron spectroscopy (UPS) and X-ray absorption spectroscopy in total fluorescence yield mode (XAS-TFY), intrinsic Si at the bottom of the nanoscale (i-nano-Si) turns into strong p- or n-Si by embedding in silicon nitride (SiN) or silicon dioxide (SiO), respectively. The associated Nanoscale Electronic Structure Shift Induced by Anions at Surfaces (NESSIAS) creates a p/n junction in i-nano-Si by the quantum-chemical impact of SiN- vs SiO-coating, providing energy landscapes to accumulate electrons (holes) when SiO- (SiN-) coated, with free charge carriers provided by metallic interconnects.

Special Issue: 2D Layered Nanomaterials and Heterostructures for Electronics, Optoelectronics, and Sensing.

Since the first report in 2004 on the electronic properties of graphene exfoliated from graphite [...

Tracking life and death of carbon nitride supports in platinum-catalyzed vinyl chloride synthesis.

Deactivation of metal-based catalysts for vinyl chloride synthesis via acetylene hydrochlorination is often dictated by indispensable, catalytically-active carbon supports, but underlying mechanisms remain unclear. Carbon nitrides offer an attractive platform for studying them thanks to ordered structure and high N-content, which facilitates coking. Herein, we monitor the life and death of carbon nitride supports for Pt single atoms in acetylene hydrochlorination, demonstrating that specific N-functionalities and their restructuring cause distinct deactivation mechanisms.

Mild Temperature Thermal Treatments of Gold-Exfoliated Monolayer MoS.

Monolayer molybdenum disulfide is considered an extremely promising two-dimensional material for innovative electronics due to its direct bandgap and high charge-carrier mobility. The optical and electronic properties of monolayer MoS can, however, be strongly influenced by the specific synthesis route, posing challenges for industrial-scale production. In this study, we investigated the effects of moderate temperature thermal treatments under a controlled O atmosphere on the properties of monolayer MoS flakes.

Competing pathways to aromaticity governed by amine dehydrogenation and metal-organic complexation in on-surface synthesis.

We investigated the reactivity of a -dichlorovinyl-carbazole precursor in the on-surface synthesis approach. Our findings reveal that, on the Au(111) surface, the thermally-induced dehalogenation reaction led to the formation of cumulene dimers. Contrastingly, the more reactive Cu(111) surface promoted the formation of a polyheterocyclic compound exhibiting extended aromaticity.

Novel Insights into Enhanced Stability of Li-Rich Layered and High-Voltage Olivine Phosphate Cathodes for Advanced Batteries through Surface Modification and Electron Structure Design.

The design of cathode/electrolyte interfaces in high-energy density Li-ion batteries is critical to protect the surface against undesirable oxygen release from the cathodes when batteries are charged to high voltage. However, the involvement of the engineered interface in the cationic and anionic redox reactions associated with (de-)lithiation is often ignored, mostly due to the difficulty to separate these processes from chemical/catalytic reactions at the cathode/electrolyte interface. Here, a new electron energy band diagrams concept is developed that includes the examination of the electrochemical- and ionization- potentials evolution upon batteries cycling.

Physical Delithiation of Epitaxial LiCoO Battery Cathodes as a Platform for Surface Electronic Structure Investigation.

We report a novel delithiation process for epitaxial thin films of LiCoO(001) cathodes using only physical methods, based on ion sputtering and annealing cycles. Preferential Li sputtering followed by annealing produces a surface layer with a Li molar fraction in the range 0.5 < < 1, characterized by good crystalline quality.

On-Surface Synthesis of Unsaturated Hydrocarbon Chains through C-S Activation.

We use an on-surface synthesis approach to drive the homocoupling reaction of a simple dithiophenyl-functionalized precursor on Cu(111). The C-S activation reaction is initiated at low annealing temperature and yields unsaturated hydrocarbon chains interconnected in a fully conjugated reticulated network. High-resolution atomic force microscopy imaging reveals the opening of the thiophenyl rings and the presence of trans- and cis-oligoacetylene chains as well as pentalene units.

Correction: Tuning the charge carrier mobility in few-layer PtSe films by Se : Pt ratio.

[This corrects the article DOI: 10.1039/D1RA04507E.].

Tuning the charge carrier mobility in few-layer PtSe films by Se : Pt ratio.

Recently, few-layer PtSe films have attracted significant attention due to their properties and promising applications in high-speed electronics, spintronics and optoelectronics. Until now, the transport properties of this material have not reached the theoretically predicted values, especially with regard to carrier mobility. In addition, it is not yet known which growth parameters (if any) can experimentally affect the carrier mobility value.

Energy Level Alignment at the Cobalt Phosphate/Electrolyte Interface: Intrinsic Stability vs Interfacial Chemical Reactions in 5 V Lithium Ion Batteries.

The intrinsic stability of the 5 V LiCoPO-LiCoPO thin-film (carbon-free) cathode material coated with MoO thin layer is studied using a comprehensive synchrotron electron spectroscopy in situ approach combined with first-principle calculations. The atomic-molecular level study demonstrates fully reversible electronic properties of the cathode after the first electrochemical cycle. The polyanionic oxide is not involved in chemical reactions with the fluoroethylene-containing liquid electrolyte even when charged to 5.

Modular Assembly of Vibrationally and Electronically Coupled Rhenium Bipyridine Carbonyl Complexes on Silicon.

Hybrid inorganic/organic heterointerfaces are promising systems for next-generation photocatalytic, photovoltaic, and chemical-sensing applications. Their performance relies strongly on the development of robust and reliable surface passivation and functionalization protocols with (sub)molecular control. The structure, stability, and chemistry of the semiconductor surface determine the functionality of the hybrid assembly.

Atomically-Precise Texturing of Hexagonal Boron Nitride Nanostripes.

Monolayer hexagonal boron nitride (hBN) is attracting considerable attention because of its potential applications in areas such as nano- and opto-electronics, quantum optics and nanomagnetism. However, the implementation of such functional hBN demands precise lateral nanostructuration and integration with other two-dimensional materials, and hence, novel routes of synthesis beyond exfoliation. Here, a disruptive approach is demonstrated, namely, imprinting the lateral pattern of an atomically stepped one-dimensional template into a hBN monolayer.

Turning Low-Nanoscale Intrinsic Silicon Highly Electron-Conductive by SiO Coating.

Impurity doping in silicon (Si) ultra-large-scale integration is one of the key challenges which prevent further device miniaturization. Using ultraviolet photoelectron spectroscopy and X-ray absorption spectroscopy in the total fluorescence yield mode, we show that the lowest unoccupied and highest occupied electronic states of ≤3 nm thick SiO-coated Si nanowells shift by up to 0.2 eV below the conduction band and ca.

Morphological characterization and electronic properties of pristine and oxygen-exposed graphene nanoribbons on Ag(110).

Graphene nanoribbons (GNRs) are at the frontier of research on graphene materials since the 1D quantum confinement of electrons allows for the opening of an energy gap. GNRs of uniform and well-defined size and shape can be grown using the bottom-up approach, i.e.

Hydrogen Bonding of Ammonia with (H,OH)-Si(001) Revealed by Experimental and Ab Initio Photoelectron Spectroscopy.

Combining experimental and ab initio core-level photoelectron spectroscopy (periodic DFT and quantum chemistry calculations), we elucidated how ammonia molecules bond to the hydroxyls of the (H,OH)-Si(001) model surface at a temperature of 130 K. Indeed, theory evaluated the magnitude and direction of the N 1s (and O 1s) chemical shifts according to the nature (acceptor or donor) of the hydrogen bond and, when confronted to experiment, showed unambiguously that the probe molecule makes one acceptor and one donor bond with a pair of hydroxyls. The consistency of our approach was proved by the fact that the identified adsorption geometries are precisely those that have the largest binding strength to the surface, as calculated by periodic DFT.

Electronic Structures of the Vanadium-Intercalated and Substitutionally Doped Transition-Metal Dichalcogenides TiVSe.

The electronic structures of V-intercalated TiSe and substitutionally doped dichalcogenides TiVSe have been studied using soft X-ray photoelectron, resonant photoelectron, and absorption spectroscopies. In the case of the substitution of Ti by V, the formation of coherently oriented structural fragments VSe and TiSe is observed and a small charge transfer between these fragments is found. Intercalation of the V atoms into TiSe leads to charge transfer from the V atoms to the Ti atoms with the formation of covalent complexes Ti-Se-V-Se-Ti.

Highly Hydrophilic Gold Nanoparticles as Carrier for Anticancer Copper(I) Complexes: Loading and Release Studies for Biomedical Applications.

Gold nanoparticles (AuNPs), which are strongly hydrophilic and dimensionally suitable for drug delivery, were used in loading and release studies of two different copper(I)-based antitumor complexes, namely [Cu(PTA)] [BF] (A; PTA = 1, 3, 5-triaza-7-phosphadamantane) and [HB(pz)Cu(PCN)] (B; HB(pz) = tris(pyrazolyl)borate, PCN = tris(cyanoethyl)phosphane). In the homoleptic, water-soluble compound A, the metal is tetrahedrally arranged in a cationic moiety. Compound B is instead a mixed-ligand (scorpionate/phosphane), neutral complex insoluble in water.

Synthesis of corrugated C-based nanostructures by Br-corannulene oligomerization.

The structure and electronic properties of carbon-based nanostructures obtained by metal surface assisted synthesis is highly dependent on the nature of the precursor molecule. Here, we report on a combined scanning tunneling microscopy, soft X-ray spectroscopy and density functional theory investigation on the surface assisted polymerization of Br-corannulene at Ag(110) and on the possibility of building a mesh of π-conjugated polymers starting from buckyball shaped molecules. Indeed, the corannulene units form one-molecule-wide ribbons in which the natural concavity of the precursor molecule is maintained.

Guest-Host Chemical Bonding and Possibility of Ordering of Intercalated Metals in Transition-Metal Dichalcogenides.

The comparison of the specifics of the guest-host chemical bonding in the materials with (Fe TiSe) and without (Fe TiTe) ordering of the iron atoms was performed. For this purpose the electronic structure of the materials were studied using X-ray photoelectron spectroscopy, X-ray absorption spectroscopy, resonant X-ray photoelectron spectroscopy, and theoretical calculations (total density of states, partial density of states, and multiplet calculations). For the iron-intercalated TiTe compound iron-chalcogen bonds are formed, whereas the formation of iron-iron bonds is most typical for the iron-intercalated TiSe compound.