(Invited) In-Vacuo Studies of Transition Metal Dichalcogenide Synthesis and Layered Material Integration

Abstract

Using an in-vacuo deposition/characterization tool, we study the 2D materials synthesized by molecular beam epitaxy and the interfaces formed between layered materials and in-vacuo deposited metals. The metal-2D interface is probed with x-ray photoelectron spectroscopy. Full details of sample preparation and transition metal dichalcogenide synthesis are provided. Furthermore a detailed study of in-vacuo deposited Ti on graphene, shows that while there is clear evidence of Ti carbide formation, there is no conclusive evidence of reactions with the graphene layer. Instead the carbide forms from a combination of adventitious carbon on the graphene surface, and carbon added via the deposition process.

Metal Nitride Electrode Stress and Chemistry Effects on Phase and Polarization Response in Ferroelectric Hf0.5Zr0.5O2 Thin Films

“…N:Ta ratios for witness blanket TaN electrode layers were determined using a PHI Versaprobe X‐Ray Photoelectron Spectroscopy III instrument utilizing monochromated Al Kα radiation with an incidence angle of 45°, a pass energy of 26 eV, an anode bias of 15 kV, and an anode power of 50 W. Angle‐resolved XPS measurements were made using a Scientia Omicron system equipped with Al Kα radiation and an R3000 Analyzer described elsewhere. [ 70 ] XPS spectra were fit using KolXPD spectral fitting software. Shirley backgrounds were fit for each spectrum, and Voigt peaks were fit to each known feature to assess and compare amplitudes.…”

The influence of titanium adhesion layer oxygen stoichiometry on thermal boundary conductance at gold contacts

“…XPS data were acquired with a monochromated x-ray source at a pass energy of 50 eV in a UHV system described elsewhere. 41 Figure 1(a) shows XPS spectra of the O 1s core level in three distinct Ti films deposited on SiO 2 substrates at different deposition rates. The O 1s spectra are each composed of two features: a peak at 530.5 eV, corresponding to Ti-O bonds, 42 and a broader feature at the high binding energy shoulder which is attributed to hydrocarbon species.…”

Thermal stability of hafnium zirconium oxide on transition metal dichalcogenides

“…WSe 2 was grown on a 1 x 1 cm square of highly ordered pyrolytic graphite (HOPG) from SPI Supplies [38] using molecular beam epitaxy (MBE) in an ultra-high vacuum (UHV) system described elsewhere [44]. The HOPG crystal was outgassed for approximately 12 h in the MBE chamber at 250 °C.…”

“…Sequential heating and XPS were performed on the HZO/TMDC samples in the same UHV chamber described previously [44]. XPS spectra were taken using a monochromated Al Kα X-ray source at 300 W with a Scienta Omicron R3000 analyzer at a pass energy of 50 eV.…”