Photoluminescence and charge transfer in the prototypical 2D/3D semiconductor heterostructure MoS2/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 more traditional three-dimensional (3D) semiconductors is an important challenge for the implementatio...

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Bibliographic Details
Published in:Applied physics letters 2021-12, Vol.119 (23)
Main Authors: Rojas-Lopez, Rafael R., Brant, Juliana C., Ramos, Maíra S. O., Castro, Túlio H. L. G., Guimarães, Marcos H. D., Neves, Bernardo R. A., Guimarães, Paulo S. S.
Format: Article
Language:English
Subjects:
Applied physics
Boron nitride
Charge exchange
Charge transfer
Electronic devices
Emission spectra
Excitons
Gallium arsenide
Heterojunctions
Heterostructures
Molybdenum disulfide
Monolayers
Optical properties
Photoluminescence
Photovoltaic cells
Solar cells
Substrates
Two dimensional materials
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Summary: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 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 MoS2 with GaAs, it is possible to develop high quality photodetectors and solar cells. Here, we present a study of effects of intrinsic GaAs, p-doped GaAs, and n-doped GaAs substrates on the photoluminescence of monolayer MoS2. We observe a decrease in an order of magnitude in the emission intensity of MoS2 in all MoS2/GaAs heterojunctions, when compared to a control sample consisting of a MoS2 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 substrates, a dependence that we relate to the static charge exchange between MoS2 and the substrates when the junction is formed. Scanning Kelvin probe microscopy measurements of heterojunctions suggest type-I band alignments, so that excitons generated on the MoS2 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.
ISSN:0003-6951
1077-3118
DOI:10.1063/5.0068548