posted on 2020-04-03, 16:11authored byEunah Kim, Chanwoo Lee, Jungeun Song, Soyeong Kwon, Bora Kim, Dae Hyun Kim, Tae Joo Park, Mun Seok Jeong, Dong-Wook Kim
Metal
and transition-metal dichalcogenide (TMD) hybrid systems
have been attracting growing research attention because exciton–plasmon
coupling is a desirable means of tuning the physical properties of
TMD materials. Competing effects of metal nanostructures, such as
the local electromagnetic field enhancement and luminescence quenching,
affect the photoluminescence (PL) characteristics of metal/TMD nanostructures.
In this study, we prepared TMD MoS2 monolayers on hexagonal
arrays of Au nanodots and investigated their physical properties by
micro-PL and surface photovoltage (SPV) measurements. MoS2 monolayers on bare Au nanodots exhibited higher PL intensities than
those of MoS2 monolayers on 5-nm-thick Al2O3-coated Au nanodots. The Al2O3 spacer
layer blocked charge transfer at the Au/MoS2 interface
but allowed the transfer of mechanical strain to the MoS2 monolayers on the nanodots. The SPV mapping results revealed not
only the electron-transfer behavior at the Au/MoS2 contacts
but also the lateral drift of charge carriers at the MoS2 surface under light illumination, which corresponds to nonradiative
relaxation processes of the photogenerated excitons.