Construction of bilayer PdSe2 on epitaxial graphene

摘要

Two-dimensional （2D） materials have received significant attention due totheir unique physical properties and potential applications in electronics andoptoelectronics. Recent studies have demonstrated that exfoliated PdSe2, alayered transition metal dichalcogenide （TMD）, exhibits ambipolar field-effecttransistor （FET） behavior with notable performance and good air stability, andthus serves as an emerging candidate for 2D electronics. Here, we report thegrowth of bilayer PdSe2 on a graphene-SiC（0001） substrate by molecular beamepitaxy （MBE）. A bandgap of 1.15±0.07 eV was revealed by scanning tunnelingspectroscopy （STS）. Moreover, a bandgap shift of 0.2 eV was observed in PdSe2layers grown on monolayer graphene as compared to those grown on bilayergraphene. The realization of nanoscale electronic junctions with atomicallysharp boundaries in 2D PdSe2 implies the possibility of tuning its electronicor optoelectronic properties. In addition, on top of the PdSe2 bilayers, PdSe2nanoribbons and stacks of nanoribbons with a fixed orientation have beenfabricated. The bottom-up fabrication of low-dimensional PdSe2 structures isexpected to enable substantial exploration of its potential applications.