1 research outputs found
Photoluminescence and charge transfer in the prototypical 2D/3D semiconductor heterostructure MoS<sub>2</sub>/GaAs
The new generation of two-dimensional (2D) materials has shown a broad range
of applications for optical and electronic devices. Understanding the
properties of these materials when integrated with the more traditional
three-dimensional (3D) semiconductors is an important challenge for the
implementation of ultra-thin electronic devices. Recent observations have shown
that by combining MoS with GaAs it is possible to develop high quality
photodetectors and solar cells. Here, we present a study of the effects of
intrinsic GaAs, p-doped GaAs, and n-doped GaAs substrates on the
photoluminescence of monolayer MoS. We observe a decrease of an order of
magnitude in the emission intensity of MoS in all MoS/GaAs
heterojunctions, when compared to a control sample consisting of a MoS
monolayer isolated from GaAs by a few layers of hexagonal boron nitride. We
also see a dependence of the trion to A-exciton emission ratio in the
photoluminescence spectra on the type of substrate, a dependence that we relate
to the static charge exchange between MoS and the substrates when the
junction is formed. Scanning Kelvin probe microscopy measurements of the
heterojunctions suggest type-I band alignments, so that excitons generated on
the MoS monolayer will be transferred to the GaAs substrate. Our results
shed light on the charge exchange leading to band offsets in 2D/3D
heterojunctions which play a central role in the understanding and further
improvement of electronic devices.Comment: Accepted in Applied Physics Letter