Nonlinear Optical Signatures of Transition from Semiconductor to Semimetal in PtSe2
Kislyakov, Ivan M.
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The demand for an ultrabroad optical material with a bandgap tunable from zero to at least 1~2 eV has been one of the driving forces for exploring new two-dimensional (2D) materials since the emergence of graphene, transition metal dichalcogenides and black phosphorus. As an ultra-broadband 2D material with energy bandgap ranging from 0 to 1.2 eV, PtSe2 shows much better air stability than its analogue, black phosphorous. In this work, the superior nonlinear optical performance, ultrafast dynamics of layered PtSe2 and signatures of transition from semiconductor to semimetal have been systematically studied. Combining with rate equations, first principle calculation and electrical measurements, we provided a comprehensive understanding about the evolution of nonlinear absorption and carrier dynamics with increasing layer thickness, indicating its promising potential in nanophotonic devices such as infrared detector, optical switches and saturable absorber.