What happens when transition metal trichalcogenides are interfaced with gold?

Abstract

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. Graphical abstract I–V characteristics of (a) TiS3, (b) ZrS3, and (c) HfS3

Strong Metal–Sulfur Hybridization in the Conduction Band of the Quasi-One-Dimensional Transition-Metal Trichalcogenides: TiS3 and ZrS3

“…In TiS 3 , the Ti 2p 3/2 and 2p 1/2 core level binding energies are 455.9 and 461.9 eV, respectively, and for the ZrS 3 , the Zr 3p 3/2 and 3p 1/2 binding energies are 332.1 and 345.7 eV. These values are consistent with previous XPS measurements on TiS 3 ,,,− and ZrS 3 . − Because of the complication just mentioned above and because TiS 3 and ZrS 3 are strongly n-type, using these XPS binding energies is an overestimate of the energy needed to place E F in the XAS S 2p, Zr 3p, and Ti 2p edges, so discrepancies are addressed by using the onset edges observed in XAS and the Ca 2p edges from the CaCO 3 present in the epoxy as a reference in the case of ZrS 3 . Because both TiS 3 ,,− ,, and ZrS 3 , are strongly n-type materials, with the distance from the valence band to the Fermi level approximately equal to the band gap, , the onset of states in XAS should occur directly at E f .…”

Layered GeI2: A wide-bandgap semiconductor for thermoelectric applications–A perspective

“…A stable GeI 2 surface with suppressed phonon scattering, when taken together with the ease with which the bandgap of GeI 2 can be widened further (Dhingra et al, 2022a), will augment its versatility for high-temperature thermoelectric applications. Finally, it must be noted that as is the case when it comes to forming contacts with most 2D materials (S. Schulman et al, 2018;Ang et al, 2021;Zheng et al, 2021;Dhingra et al, 2020a;Dhingra et al, 2021c;Dhingra et al, 2022c;Dhingra et al, 2022d), forming Ohmic contacts to GeI 2 may not be trivial; especially because the germanium rich surface could adversely affect the contact potentials for GeI 2 -based nanodevices (Dhingra et al, 2022b). This Perspective, thus, acts as a guide for future studies dealing with the GeI 2 -based thermoelectric nanodevices.…”

Electronic transport and polarization-dependent photoresponse in few-layered hafnium trisulfide (HfS3) nanoribbons

“…The excess of sulfur accumulated at the colder end of the ampoule, while millimeter long HfS 3 crystals were found on the hafnium foil and in some locations on the quartz surface. As discussed in our previous works, 23,55 HfS 3 is susceptible to surface oxidation, so the crystals were stored in a nitrogen glove box before the use.…”

“…However, the energy of the red laser is close to the measured indirect gap, suggesting the possibility of some optical excitations at 685 nm. In addition, defects and the p-type layer at the surface of HfS 3 caused by the surface oxidation 23,55 could add states at the band edge, making the HfS 3 optically active at energies lower than the band gap. Thus, the generation of photocarriers using the red light source is plausible and consistent with the laser energy-dependent phototransistor measurements, which show very small photoresponse at 685 nm compared to the green and blue lasers with energies larger than the direct optical band gap of HfS 3 .…”