Energy transfer in a type-I van der Waals heterostructure of WSe₂/PtSe₂

Abstract

Energy transfer of a van der Waals heterostructure formed by monolayers of WSe2 and PtSe2 is studied by steady-state photoluminescence and time-resolved transient absorption spectroscopy. The heterostructure sample is fabricated by transferring a mechanically exfoliated WSe2 monolayer onto a PtSe2 monolayer film obtained by chemical vapor deposition. The sample is thermally annealed to improve the interface quality. Photoluminescence of the heterostructure is quenched by 4 times compared to the individual WSe2 monolayer, indicating excitation transfer from WSe2 to PtSe2 . Femtosecond transient absorption measurements with two configurations show that both the electrons and the holes can transfer from WSe2 to PtSe2 on a sub-picosecond time scale, while neither can transfer from PtSe2 to WSe2. These results indicate that WSe2 and PtSe2 monolayers form a type-I band alignment with both the conduction band minimum and the valence band maximum in the PtSe2 layer.

A review of Ga2O3 deep-ultraviolet metal–semiconductor Schottky photodiodes

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