Correlating Nanocrystalline Structure with Electronic Properties in 2D Platinum Diselenide

Abstract

Platinum diselenide (PtSe 2 ) 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 PtSe 2 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 PtSe 2 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 PtSe 2 toward numerous applications.

Abnormal linear dichroism transition in two-dimensional PdPS

“…4a. 24,25 As the thickness increases, red shifts of ∼3 and ∼2 cm −1 were evidently observed for the peak positions of 102 and 489 cm −1 , respectively, indicating the strong interlayer coupling of PdPS shown in Fig. 4b and c.…”

Stacking Polymorphism in PtSe2 Drastically Affects Its Electromechanical Properties

“…We argue that a correlation of different techniques to HRTEM or XRD analysis might yield conclusive evidence of the stacking phases, similar to a finger print. [ 33 ] Together with electromechanical measurements, the Seebeck coefficient might be a useful indicator for sample quality. We estimate the Seebeck coefficient for a temperature gradient from 300 to 400 K as function of the carrier concentration for different stacking phases (see Figure 4b with method details in the Supporting Information).…”

“…[ 20 , 42 ] Measurements of the gauge factors and Seebeck coefficients were undertaken as published earlier. [ 33 ]…”

“…Experimental errors of the charge carrier concentration, Gauge Factors and Seebeck coefficients were estimated from Lukas et al. [ 33 ]…”

“…Importantly, the symmetry reduction from the high‐symmetry 1T O phase to lower‐symmetry stacking phases can lead to semiconducting properties. This has a significant impact on the electronic characteristics of polycrystalline thin films: For example, other stacking phases might help to explain the large discrepancy of electronic mobilities of PtSe 2 found in literature, ranging from lower than 1 [ 19 , 32 , 33 ] to 625 cm −2 V −1 s −1 . [ 22 ]…”