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The celebrated electronic properties of graphene 1 , 2 have opened the way for materials just one atom thick 3 to be used in the post-silicon electronic era 4 . An important milestone was the creation of heterostructures based on graphene and other two-dimensional crystals, which can be assembled into three-dimensional stacks with atomic layer precision 5 , 6 , 7 . Such layered structures have already demonstrated a range of fascinating physical phenomena 8 , 9 , 10 , 11 , and have also been used in demonstrating a prototype field-effect tunnelling transistor 12 , which is regarded to be a candidate for post-CMOS (complementary metal-oxide semiconductor) technology. The range of possible materials that could be incorporated into such stacks is very large. Indeed, there are many other materials with layers linked by weak van der Waals forces that can be exfoliated 3 , 13 and combined together to create novel highly tailored heterostructures. Here, we describe a new generation of field-effect vertical tunnelling transistors where two-dimensional tungsten disulphide serves as an atomically thin barrier between two layers of either mechanically exfoliated or chemical vapour deposition-grown graphene. The combination of tunnelling (under the barrier) and thermionic (over the barrier) transport allows for unprecedented current modulation exceeding 1 × 10 6 at room temperature and very high ON current. These devices can also operate on transparent and flexible substrates. A tunnelling transistor based on stacks of chemically grown graphene and other two-dimensional layers shows record performance.

Capacitance measurements provide a powerful means of probing the density of states. The technique has proved particularly successful in studying 2D electron systems, revealing a number of interesting many-body effects. Here, we use large-area high-quality graphene capacitors to study behavior of the density of states in this material in zero and high magnetic fields. Clear renormalization of the linear spectrum due to electron–electron interactions is observed in zero field. Quantizing fields lead to splitting of the spin- and valley-degenerate Landau levels into quartets separated by interaction-enhanced energy gaps. These many-body states exhibit negative compressibility but the compressibility returns to positive in ultrahigh B. The reentrant behavior is attributed to a competition between field-enhanced interactions and nascent fractional states.

Integrated logic circuits using atomically thin, two‐dimensional (2D) materials offer several potential advantages compared to established silicon technologies such as increased transistor density, circuit complexity, and lower energy dissipation leading to scaling benefits. In this article, a novel approach to achieve tunable doping in 2D semiconductors is explored to achieve complementary transistors and logic integration. By selectively transferring WSe 2 onto hBN and SiO 2 substrates, complementary transistor behavior (n‐ and p‐type) was achieved using a UV light source and electrostatic activation. Furthermore, advanced characterization techniques, including high‐resolution transmission electron microscopy (HRTEM) and Kelvin probe force microscopy (KPFM), provided insights into the chemical composition and surface potential changes after UV writing. Finally, a logic inverter was successfully implemented using selectively photo‐induced doped WSe 2 transistors, showcasing the potential for practical logic applications. This innovative method opens new avenues for designing energy‐efficient and reconfigurable 2D semiconductor circuits, addressing key challenges in modern electronics.

This paper describes the high-rate (~1.5 μm/min) growth of Si films on Si supporting substrates with (100) crystallographic orientation at 600 °C, 800 °C, and 1000 °C in a vacuum environment of ~1 × 10−5 mbar using electron beam (e-beam) evaporation. The microstructure, crystallinity, and conductivity of such films were investigated. It was established that fully crystalline (Raman spectroscopy, EBSD) and stress-free epi-Si layers with a thickness of approximately 50 µm can be fabricated at 1000 °C, while at 600 °C and 800 °C, some poly-Si inclusions were observed using Raman spectroscopy. Hall effect measurements showed that epi-Si layers deposited at 1000 °C had resistivity, carrier concentration, and mobility comparable to those obtained for c-Si wafers fabricated through ingot growth and wafering using the same solar grade Si feedstock used for the e-beam depositions. The dislocation densities were determined to be ∼2 × 107 cm−2 and ∼5 × 106 cm−2 at 800 and 1000 °C, respectively, using Secco etch. The results highlight the potential of e-beam evaporation as a promising and cost-effective alternative to conventional CVD for the growth of epi-Si layers and, potentially, epi-Si wafers. Some of the remaining technical challenges of this deposition technology are briefly indicated and discussed.

Ocean carbon sink is an emerging and interdisciplinary research area that plays a vital role in the global carbon cycle. This paper reviews recent scientific advancements in ocean carbon sink research, focusing on the mechanisms for capturing, utilizing, and sequestering atmospheric CO 2 , and highlights its contribution to climate change mitigation and adaptation. Using bibliometric analysis based on CiteSpace and data from the Web of Science and Scopus, we examine research hotspots and topic evolution through country collaboration, journal co-citation, and keyword co-occurrence networks. The findings show that ocean carbon sink research is shaped by complex scientific uncertainties and the integration of multiple disciplines. Current research hotspots include scientific advances, technological innovation, and governance challenges related to sustainable development. In general, recent studies emphasize the role of carbon sink, the value of nature, and the importance of precautionary management. This paper underlines the need for coordination between scientific and social dimensions of carbon sink functions, and it draws attention to the ethical aspects of carbon sink governance. It advocates for multi-stakeholder participation, precautionary governance, and policy-based financial system to support climate resilience and foster the sustainable development of the oceans.

The celebrated electronic properties of graphene have opened the way for materials just one atom thick to be used in the post-silicon electronic era. An important milestone was the creation of heterostructures based on graphene and other two-dimensional crystals, which can be assembled into three-dimensional stacks with atomic layer precision. Such layered structures have already demonstrated a range of fascinating physical phenomena, and have also been used in demonstrating a prototype field-effect tunnelling transistor, which is regarded to be a candidate for post-CMOS (complementary metal-oxide semiconductor) technology. The range of possible materials that could be incorporated into such stacks is very large. Indeed, there are many other materials with layers linked by weak van der Waals forces that can be exfoliated and combined together to create novel highly tailored heterostructures. Here, we describe a new generation of field-effect vertical tunnelling transistors where two-dimensional tungsten disulphide serves as an atomically thin barrier between two layers of either mechanically exfoliated or chemical vapour deposition-grown graphene. The combination of tunnelling (under the barrier) and thermionic (over the barrier) transport allows for unprecedented current modulation exceeding 1 10 super(6) at room temperature and very high ON current. These devices can also operate on transparent and flexible substrates.

Capacitance measurements provide a powerful means of probing the density of states. The technique has proved particularly successful in studying 2D electron systems, revealing a number of interesting many-body effects. Here, we use large-area high-quality graphene capacitors to study behavior of the density of states in this material in zero and high magnetic fields. Clear renormalization of the linear spectrum due to electron-electron interactions is observed in zero field. Quantizing fields lead to splitting of the spin- and valley-degenerate Landau levels into quartets separated by interaction-enhanced energy gaps. These many-body states exhibit negative compressibility but the compressibility returns to positive in ultrahigh B. The reentrant behavior is attributed to a competition between field-enhanced interactions and nascent fractional states.

The annual increase in the areal density of hard disk drives has recently slowed from 60% per annum to 30% per annum as fundamental limits are approached. Current data storage techniques are not thought to be sufficient to achieve storage densities of 1Tbit/in2 and beyond. Patterned media has therefore been suggested as one of the possible techniques to extend the areal density beyond the current limits by fabricating single domain islands out of continuous thin film magnetic media. Co/Pt multilayered thin films were deposited by e-beam evaporation to enhance their strong interfacial perpendicular anisotropy, large coercivities and high squareness. The anisotropy of Co/Pt multilayers is derived from interface rather than crystalline anisotropy making them good candidates for patterning. E-beam lithography was then used to pattern Go/Pt multilayered films with perpendicular anisotropy using an Au hard mask and Ar ion milling. Islands of various sizes from 500nm with a periodicity of 1µm down to 20nm with a periodicity of 50nm have been fabricated. This corresponds to an areal density of 300Gbits/in2. Hr (high resolution) -MFM was used to investigate the domain structure of islands of different sizes. Contact recording experiments on larger islands (2µm to 200nm) are also presented. The size distribution of the e-beam fabricated islands was also calculated from high resolution SEM images. Hr-MFM with in-situ applied field was used to directly determine the switching field distributions (SFD) and hysteresis loops of the islands. An initial temperature study was also carried out to determine the thermal stability of the fabricated islands. Finally, further work which could be carried out to improve the work in this thesis is discussed.

Near Ambient Pressure Scanning Photoelectron Microscopy adds to the widely used photoemission spectroscopy and its chemically selective capability two key features: (i) the possibility to chemically analyse samples in a more realistic environmental, gas pressure condition, and (ii) the capability to investigate a system at the relevant spatial scale. To achieve these goals the approach developed at the ESCA Microscopy beamline at the Elettra Synchrotron facility combines the submicron lateral resolution of a Scanning Photoelectron Microscope with a custom designed Near Ambient Pressure Cell where a gas pressure up to 0.1 mbar is confined inside it around the sample. In this manuscript a review of experiments performed with this unique setup will be presented to illustrate its potentiality in both fundamental and applicative research such as the oxidation reactivity and gas sensitivity of metal oxides and semiconductors. In particular the capability to do operando experiment with this setup opens the possibility to perform investigations with active devices to properly address the real nature of the studied systems, because it can yield to more conclusive results when microscopy and spectroscopy are simultaneously combined in a single technique.