What happens when transition metal trichalcogenides are interfaced with gold?

Transition metal trichalcogenides (TMTs) are two-dimensional (2D) systems with quasi-one-dimensional (quasi-1D) chains. These 2D materials are less susceptible to undesirable edge defects, which enhances their promise for low-dimensional optical and electronic device applications. However, so far, the performance of 2D devices based on TMTs has been hampered by contact-related issues. Therefore, in this review, a diligent effort has been made to both elucidate and summarize the interfacial interactions between gold and various TMTs, namely, In4Se3, TiS3, ZrS3, HfS3, and HfSe3. X-ray photoemission spectroscopy data, supported by the results of electrical transport measurements, provide insights into the nature of interactions at the Au/In4Se3, Au/TiS3, Au/ZrS3, Au/HfS3, and Au/HfSe3 interfaces. This may help identify and pave a path toward resolving the contemporary contact-related problems that have plagued the performance of TMT-based nanodevices

Indium segregation to the selvedge of In\u3csub\u3e4\u3c/sub\u3eSe\u3csub\u3e3\u3c/sub\u3e (001)

Thermal motion of the surface atoms will lead to a decrease in photoemission intensity, while surface segregation may result in an increase of some phostoemission intensities. For In4Se3(001), both effects are seen. The Debye–Waller factor plot, based on the temperature dependent X-ray photoemission spectroscopy (XPS) measurements on In4Se3(001), suggests an upper bound of 203 ± 6 K for the effective Debye temperature, based on the surface component of the In 3d5/2 core-level. Indium is found to segregate to selvedge (subsurface region) of the crystal

Physical and Electronic Properties of Two-Dimensional Layered Materials: In4Se3, TiS3, ZrS3, HfS3, and GeI2

As transistor widths shrink down to a few nanometers, two-dimensional (2D) materials can help combat gate leakage and boost the ON-state current. These materials can also endure considerable gate biases without going through an electrical breakdown, implying devices based on these materials may not require an insulating gate dielectric. However, as things stand, 2D semiconductors that are scalable down to the nanometer range are few and far between because edge scattering and edge states dominate for transistors narrower than 10 nm. Furthermore, the transfer of 2D semiconductor flakes is not amenable to large scale low-dimensional device manufacturing. One logical and effective route to circumvent this ordeal would be to look for 2D materials that possess quasi-one-dimensional (quasi-1D) chains where the undesirable edge effects are suppressed. Therefore, the research presented in this dissertation is dedicated to the investigation and understanding of the physical and electronic properties of some of the 2D materials lacking the abovementioned edge disorders. The quasi-1D materials whose physics is explored in this work are: In4Se3, TiS3, ZrS3, HfS3, and GeI2. Chemically, these materials are dissimilar in that In4Se3, TiS3, ZrS3, HfS3 are all transition metal trichalcogenides (TMTs), whereas GeI2 is not. Physically, however, they are alike as they all possess the much-coveted quasi-1D structure. Moreover, when considered together, these quasi-1D systems could add versatility to the “zoo” of 2D material “creatures”. The TMTs may be used in nanodevices relying on low- and mid-band gap semiconductors, while the wide-band gap of GeI2 may be exploited for high-temperature device applications. Eventually, the high Z of hafnium in HfS3 and the breaking of inversion symmetry at the surface of GeI2, intrinsically leading to enhanced spin-orbit coupling in these materials, would be worth capitalizing on for fabrication of semiconductor-based spintronic devices

Surface termination and Schottky-barrier formation of In\u3csub\u3e4\u3c/sub\u3eSe\u3csub\u3e3\u3c/sub\u3e(001)

The surface termination of In4Se3(001) and the interface of this layered trichalcogenide, with Au, was examined using x-ray photoemission spectroscopy. Low energy electron diffraction indicates that the surface is highly crystalline, but suggests an absence of C2v mirror plane symmetry. The surface termination of the In4Se3(001 is found, by angle-resolved x-ray photoemission spectroscopy, to be In, which is consistent with the observed Schottky barrier formation found with this n-type semiconductor. Transistor measurements confirm earlier results from photoemission, suggesting that In4Se3(001 is an n-type semiconductor, so that Schottky barrier formation with a large work function metal, such as Au, is expected. The measured low carrier mobilities could be the result of the contacts and would be consistent with Schottky barrier formation

Corrigendum: Surface termination and Schottky-barrier formation of In\u3csub\u3e4\u3c/sub\u3eSe\u3csub\u3e3\u3c/sub\u3e(001) [\u3ci\u3eSemiconductor Science and Technology\u3c/i\u3e (2020) 35 (065009) DOI: 10.1088/1361-6641/ab7e45]

Through the description of various surface terminations, the chain direction of In4Se3 in this paper [1] is implied to be in the plane of its surface. Even though the common convention for photoemission spectroscopy is to place z-axis along the surface normal, the axis perpendicular to the growth direction for this indium selenide is the crystallographic a-axis (and not the c-axis) [2–4]. Therefore, in our work the surface of In4Se3 should have been labeled (100), and not (001), to prevent any confusion that may have resulted from a less than conventional index notation. Data availability statement The data that support the findings of this study are available upon reasonable request from the authors

Perspective: Molecular transistors as substitutes for quantum information applications

International audienceApplications of quantum information science (QIS) generally rely on the generation and manipulation of qubits. Still, there are ways to envision a device with a continuous readout, but without the entangled states. This concise perspective includes a discussion on an alternative to the qubit, namely the solid-state version of the Mach–Zehnder interferometer, in which the local moments and spin polarization replace light polarization. In this context, we provide some insights into the mathematics that dictates the fundamental working principles of quantum information processes that involve molecular systems with large magnetic anisotropy. Transistors based on such systems lead to the possibility of fabricating logic gates that do not require entangled states. Furthermore, some novel approaches, worthy of some consideration, exist to address the issues pertaining to the scalability of quantum devices, but face the challenge of finding the suitable materials for desired functionality that resemble what is sought from QIS devices

Surface termination and Schottky-barrier formation of In4Se3(001)

© 2020 IOP Publishing Ltd. The surface termination of In4Se3(001) and the interface of this layered trichalcogenide, with Au, was examined using x-ray photoemission spectroscopy. Low energy electron diffraction indicates that the surface is highly crystalline, but suggests an absence of C2v mirror plane symmetry. The surface termination of the In4Se3(001) is found, by angle-resolved x-ray photoemission spectroscopy, to be In, which is consistent with the observed Schottky barrier formation found with this n-type semiconductor. Transistor measurements confirm earlier results from photoemission, suggesting that In4Se3(001) is an n-type semiconductor, so that Schottky barrier formation with a large work function metal, such as Au, is expected. The measured low carrier mobilities could be the result of the contacts and would be consistent with Schottky barrier formation11sci