TY - JOUR
T1 - Effects of composition and temperature on the exciton emission behaviors of Mo(SxSe1-x)2 monolayer
T2 - Experiment and theory
AU - Chen, Fangfang
AU - Zhou, Bin
AU - Zhang, Peng
AU - Ye, Yan
AU - Sun, Huimin
AU - Xu, Liping
AU - Zhu, Liangqing
AU - Jiang, Kai
AU - Gong, Yongji
AU - Hu, Zhigao
AU - Chu, Junhao
N1 - Publisher Copyright:
© 2020 IOP Publishing Ltd.
PY - 2020/1/22
Y1 - 2020/1/22
N2 - Exploring the excitonic behavior of two-dimensional (2D) alloys is of great significance, which not only could promote the understanding of fundamental photophysics in optoelectric devices, but could also guide the functional improvement of future applications. Here, we demonstrate the controllable synthesis of monolayer Mo(SxSe1-x)2 nanosheets using a one-step chemical vapor deposition method and systematical investigation on the exciton emission characteristics based on the temperature-dependent photoluminescence spectroscopy (PL) experiments. As a result, the tunable bandgap of Mo(SxSe1-x)2 alloys between 1.52 and 1.85 eV can be achieved, which is consistent with the theoretical results calculated by the ab initio density function theory. Besides, both the exciton and trion behaviors in Mo(SxSe1-x)2 are observed from the PL spectra at T = 80 K. More intriguingly, the differences between the emission energy of exciton and trion (ΔE), known as the dissociation energy of the trion, are positively correlated to the concentrations of the sulfur (S) elements, which is also proved by the theoretical calculation. Combining the experimental and theoretical results, the phenomena can be explained by the reduced dielectric screening effect and the increasing Fermi energy (E F) along with the increasing of sulfur in Mo(SxSe1-x)2 nanosheets, jointly leading to the increase of ΔE. Furthermore, the evolutions of ΔE in Mo(SxSe1-x)2 alloys as a function of temperature have been also discovered, which lay the foundation for the potential uses of 2D alloys in optoelectronic devices.
AB - Exploring the excitonic behavior of two-dimensional (2D) alloys is of great significance, which not only could promote the understanding of fundamental photophysics in optoelectric devices, but could also guide the functional improvement of future applications. Here, we demonstrate the controllable synthesis of monolayer Mo(SxSe1-x)2 nanosheets using a one-step chemical vapor deposition method and systematical investigation on the exciton emission characteristics based on the temperature-dependent photoluminescence spectroscopy (PL) experiments. As a result, the tunable bandgap of Mo(SxSe1-x)2 alloys between 1.52 and 1.85 eV can be achieved, which is consistent with the theoretical results calculated by the ab initio density function theory. Besides, both the exciton and trion behaviors in Mo(SxSe1-x)2 are observed from the PL spectra at T = 80 K. More intriguingly, the differences between the emission energy of exciton and trion (ΔE), known as the dissociation energy of the trion, are positively correlated to the concentrations of the sulfur (S) elements, which is also proved by the theoretical calculation. Combining the experimental and theoretical results, the phenomena can be explained by the reduced dielectric screening effect and the increasing Fermi energy (E F) along with the increasing of sulfur in Mo(SxSe1-x)2 nanosheets, jointly leading to the increase of ΔE. Furthermore, the evolutions of ΔE in Mo(SxSe1-x)2 alloys as a function of temperature have been also discovered, which lay the foundation for the potential uses of 2D alloys in optoelectronic devices.
KW - Mo(SSe)
KW - exciton emission
KW - temperature dependence
KW - two-dimensional alloys
UR - https://www.scopus.com/pages/publications/85078560863
U2 - 10.1088/1361-6528/ab646e
DO - 10.1088/1361-6528/ab646e
M3 - 文章
C2 - 31860906
AN - SCOPUS:85078560863
SN - 0957-4484
VL - 31
JO - Nanotechnology
JF - Nanotechnology
IS - 15
M1 - 155703
ER -