Abstract:
Transition metal dichalcogenides (TMDs) have been a core constituent of 2D material research
throughout the last decade. Over this time, research focus has progressively shifted from
synthesis and fundamental investigations, to exploring their properties for applied research
such as electrochemical applications and integration in electrical devices.
Due to the rapid pace of development, priority is often given to application-oriented aspects
while careful characterisation and analysis of the TMD materials themselves is occasionally
neglected. This can be particularly evident for characterisations involving X-ray photoelectron
spectroscopy (XPS), where measurement, peak-fitting, and analysis can be complex and
nuanced endeavours requiring specific expertise.
To improve the availability and accessibility of reference information, here we present a
detailed peak-fitted XPS analysis of ten transition metal chalcogenides. The materials were
synthesised as large-area thin-films on SiO2 using direct chalcogenisation of pre-deposited
metal films. Alongside XPS, the Raman spectra with several excitation wavelengths for each
material are also provided. These complementary characterisation methods can provide a more
complete understanding of the composition and quality of the material.
As material stability is a crucial factor when considering applications, the in-air thermal
stability of the TMDs was investigated after several annealing points up to 400 °C. This
delivers a trend of evolving XPS and Raman spectra for each material which improves
interpretation of their spectra while also indicating their ambient thermal limits. This provides
an accessible library and set of guidelines to characterise, compare, and discuss TMD XPS and
Raman spectra.