Correlating Nanocrystalline Structure with Electronic Properties in 2D Platinum Diselenide

Platinum diselenide (PtSe2) is a 2D material with outstanding electronic and
piezoresistive properties. The material can be grown at low temperatures in a
scalable manner, which makes it extremely appealing for many potential electronics,
photonics, and sensing applications. Here, the nanocrystalline structure
of different PtSe2 thin films grown by thermally assisted conversion (TAC)
is investigated and is correlated with their electronic and piezoresistive properties.
Scanning transmission electron microscopy for structural analysis, X-ray
photoelectron spectroscopy (XPS) for chemical analysis, and Raman spectroscopy
for phase identification are used. Electronic devices are fabricated using
transferred PtSe2 films for electrical characterization and piezoresistive gauge
factor measurements. The variations of crystallite size and their orientations
are found to have a strong correlation with the electronic and piezoresistive
properties of the films, especially the sheet resistivity and the effective charge
carrier mobility. The findings may pave the way for tuning and optimizing the
properties of TAC-grown PtSe2 toward numerous applications.