TY - JOUR

T1 - Impact of thermal annealing in forming gas on the optical and electrical properties of MoS2 monolayer

AU - Iacovella, Fabrice

AU - Koroleva, Aleksandra

AU - Rybkin, Artem G

AU - Fouskaki, Maria

AU - Chaniotakis, Nikolaos

AU - Savvidis, Pavlos

AU - Deligeorgis, George

PY - 2021/1/20

Y1 - 2021/1/20

N2 - Technological applications involving 2D MoS2 require transfer of chemical vapor deposition (CVD) grown material from its original substrate and subsequent lithographic processes. Inevitably, those steps contaminate the surface of the 2D material with polymeric residues affecting the electronic and optical properties of the MoS2. Annealing in forming gas is considered an efficient treatment to partially remove such residues. However, hydrogen also interacts with MoS2 creating or saturating sulfur vacancies. Sulfur vacancies are known to be at the origin of n-doping evident in the majority of as-grown MoS2 samples. In this context, investigating the impact of thermal annealing in forming gas on the electronic and optical properties of MoS2 monolayer is technologically important. In order to address this topic, we have systematically studied the evolution of CVD grown MoS2 monolayer using Raman spectroscopy, photoluminescence, x-ray photoelectron spectroscopy and transport measurements through a series of thermal annealing in forming gas at temperatures up to 500 °C. Efficient removal of the polymeric residues is demonstrated at temperatures as low as 200 °C. Above this value, carrier density modulation is identified by photoluminescence, x-ray photoelectron spectroscopy and electrical characterization and is correlated to the creation of sulfur vacancies. Finally, the degradation of the MoS2 single layer is verified with annealing at or above 350 °C through Raman and photocurrent measurements.

AB - Technological applications involving 2D MoS2 require transfer of chemical vapor deposition (CVD) grown material from its original substrate and subsequent lithographic processes. Inevitably, those steps contaminate the surface of the 2D material with polymeric residues affecting the electronic and optical properties of the MoS2. Annealing in forming gas is considered an efficient treatment to partially remove such residues. However, hydrogen also interacts with MoS2 creating or saturating sulfur vacancies. Sulfur vacancies are known to be at the origin of n-doping evident in the majority of as-grown MoS2 samples. In this context, investigating the impact of thermal annealing in forming gas on the electronic and optical properties of MoS2 monolayer is technologically important. In order to address this topic, we have systematically studied the evolution of CVD grown MoS2 monolayer using Raman spectroscopy, photoluminescence, x-ray photoelectron spectroscopy and transport measurements through a series of thermal annealing in forming gas at temperatures up to 500 °C. Efficient removal of the polymeric residues is demonstrated at temperatures as low as 200 °C. Above this value, carrier density modulation is identified by photoluminescence, x-ray photoelectron spectroscopy and electrical characterization and is correlated to the creation of sulfur vacancies. Finally, the degradation of the MoS2 single layer is verified with annealing at or above 350 °C through Raman and photocurrent measurements.

KW - Chemical vapor deposition growth

KW - MoS

KW - Photocurrent

KW - Photoluminescence

KW - Raman spectroscopy

KW - X-ray photoelectron spectroscopy

KW - CONTACTS

KW - DEFECTS

KW - MONOLAYER MOS2

KW - chemical vapor deposition growth

KW - PHOTOLUMINESCENCE

KW - photoluminescence

KW - MoS2

KW - VAPOR-PHASE GROWTH

KW - MECHANISMS

KW - photocurrent

KW - TRANSISTORS

KW - EVOLUTION

KW - x-ray photoelectron spectroscopy

KW - LAYER

UR - http://www.scopus.com/inward/record.url?scp=85095680507&partnerID=8YFLogxK

UR - https://www.mendeley.com/catalogue/5662185e-405f-3c01-94a7-67919532b958/

U2 - 10.1088/1361-648X/abbe76

DO - 10.1088/1361-648X/abbe76

M3 - Article

C2 - 33078711

VL - 33

JO - Journal of Physics Condensed Matter

JF - Journal of Physics Condensed Matter

SN - 0953-8984

IS - 3

M1 - 035001

ER -