Abstract
Palladium diselenide (PdSe2), a new type of two-dimensional noble metal dihalides (NMDCs), has received widespread attention for its excellent electrical and optoelectronic properties. Herein, high-quality continuous centimeter-scale PdSe2 films with layers in the range of 3L–15L were grown using Chemical Vapor Deposition (CVD) method. The absorption spectra and DFT calculations revealed that the bandgap of the PdSe2 films decreased with the increasing number of layers, which is due to the enhancement of orbital hybridization. Spectroscopic ellipsometry (SE) analysis shows that PdSe2 has significant layer-dependent optical and dielectric properties. This is mainly due to the unique strong exciton effect of the thin PdSe2 film in the UV band. In particular, the effect of temperature on the optical properties of PdSe2 films was also observed, and the thermo-optical coefficients of PdSe2 films with the different number of layers were calculated. This study provides fundamental guidance for the fabrication and optimization of PdSe2-based optoelectronic devices.
Highlights
On account of their unique layer-dependent optical and dielectric properties, two-dimensional (2D) materials have shown a broad application prospect as an essential component of novel optoelectronics devices[1,2,3,4]
The results show that the bandgap of PdSe2 films decreases with the increasing number of layers, which is consistent with the first-principle calculation
The PdSe2 films were synthesized on sapphire by an innovative three-zone Chemical Vapor Deposition (CVD) system, as shown in the schematic diagram of Fig. 1a
Summary
On account of their unique layer-dependent optical and dielectric properties, two-dimensional (2D) materials have shown a broad application prospect as an essential component of novel optoelectronics devices[1,2,3,4]. The results show that the bandgap of PdSe2 films decreases with the increasing number of layers, which is consistent with the first-principle calculation.
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