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Electronic structures of defects and magnetic impurities in MoS2 monolayers.

Lu SC, Leburton JP - Nanoscale Res Lett (2014)

Bottom Line: Specifically, we found VB group impurity elements, such as Ta, substituting Mo to achieve negative formation energy values with impurity states all sitting at less than 0.1 eV from the valence band maximum (VBM), making them the optimal p-type dopant candidates.Among the magnetic impurities such as Mn, Fe, and Co with 1, 2, and 3 magnetic moments/atom, respectively, Mn has the lowest formation energy, the most localized spin distribution, and the nearest impurity level to the conduction band among those elements.Additionally, impurity levels and Fermi level for the above three elements are closer to the conduction band than the previous work (PCCP 16:8990-8996, 2014) which shows the possibility of n-type doping by Mn, thanks to our 5 × 5 cell model.

View Article: PubMed Central - PubMed

Affiliation: Department of Electrical and Computer Engineering, and Beckman Institute, University of Illinois at Urbana-Champaign, Urbana, Illinois, 61801, USA, slu18@illinois.edu.

ABSTRACT
We provide a systematic and theoretical study of the electronic properties of a large number of impurities, vacancies, and adatoms in monolayer MoS2, including groups III and IV dopants, as well as magnetic transition metal atoms such as Mn, Fe, Co, V, Nb, and Ta. By using density functional theory over a 5 × 5 atomic cell, we identify the most promising element candidates for p-doping of MoS2. Specifically, we found VB group impurity elements, such as Ta, substituting Mo to achieve negative formation energy values with impurity states all sitting at less than 0.1 eV from the valence band maximum (VBM), making them the optimal p-type dopant candidates. Moreover, our 5 × 5 cell model shows that B, a group III element, can induce impurity states very close to the VBM with a low formation energy around 0.2 eV, which has not been reported previously. Among the magnetic impurities such as Mn, Fe, and Co with 1, 2, and 3 magnetic moments/atom, respectively, Mn has the lowest formation energy, the most localized spin distribution, and the nearest impurity level to the conduction band among those elements. Additionally, impurity levels and Fermi level for the above three elements are closer to the conduction band than the previous work (PCCP 16:8990-8996, 2014) which shows the possibility of n-type doping by Mn, thanks to our 5 × 5 cell model.

No MeSH data available.


Band structure and DOS plot of monolayer MoS2. (a) Band structure of monolayer MoS2 with the CBM and VBM both at the K point with a direct gap = 1.77 eV. (b) DOS of pristine MoS2 single layer with DOS projected on Mo 4d orbital and S 3p orbital.
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Fig2: Band structure and DOS plot of monolayer MoS2. (a) Band structure of monolayer MoS2 with the CBM and VBM both at the K point with a direct gap = 1.77 eV. (b) DOS of pristine MoS2 single layer with DOS projected on Mo 4d orbital and S 3p orbital.

Mentions: The computed band structure of MoS2 by using LDA is shown in Figure 2a. One notices that the valence band maximum (VBM) and conduction band minimum (CBM) are both located at the K point of the Brillouin zone, which indicates a direct bandgap. The valence band top originates mainly from the 4d states of Mo atom, while the conduction band bottom consists of both 4d states of Mo and 3p states of S atoms, as shown in the partial DOS plot in Figure 2b, in agreement with the previous work [23].Figure 2


Electronic structures of defects and magnetic impurities in MoS2 monolayers.

Lu SC, Leburton JP - Nanoscale Res Lett (2014)

Band structure and DOS plot of monolayer MoS2. (a) Band structure of monolayer MoS2 with the CBM and VBM both at the K point with a direct gap = 1.77 eV. (b) DOS of pristine MoS2 single layer with DOS projected on Mo 4d orbital and S 3p orbital.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4494037&req=5

Fig2: Band structure and DOS plot of monolayer MoS2. (a) Band structure of monolayer MoS2 with the CBM and VBM both at the K point with a direct gap = 1.77 eV. (b) DOS of pristine MoS2 single layer with DOS projected on Mo 4d orbital and S 3p orbital.
Mentions: The computed band structure of MoS2 by using LDA is shown in Figure 2a. One notices that the valence band maximum (VBM) and conduction band minimum (CBM) are both located at the K point of the Brillouin zone, which indicates a direct bandgap. The valence band top originates mainly from the 4d states of Mo atom, while the conduction band bottom consists of both 4d states of Mo and 3p states of S atoms, as shown in the partial DOS plot in Figure 2b, in agreement with the previous work [23].Figure 2

Bottom Line: Specifically, we found VB group impurity elements, such as Ta, substituting Mo to achieve negative formation energy values with impurity states all sitting at less than 0.1 eV from the valence band maximum (VBM), making them the optimal p-type dopant candidates.Among the magnetic impurities such as Mn, Fe, and Co with 1, 2, and 3 magnetic moments/atom, respectively, Mn has the lowest formation energy, the most localized spin distribution, and the nearest impurity level to the conduction band among those elements.Additionally, impurity levels and Fermi level for the above three elements are closer to the conduction band than the previous work (PCCP 16:8990-8996, 2014) which shows the possibility of n-type doping by Mn, thanks to our 5 × 5 cell model.

View Article: PubMed Central - PubMed

Affiliation: Department of Electrical and Computer Engineering, and Beckman Institute, University of Illinois at Urbana-Champaign, Urbana, Illinois, 61801, USA, slu18@illinois.edu.

ABSTRACT
We provide a systematic and theoretical study of the electronic properties of a large number of impurities, vacancies, and adatoms in monolayer MoS2, including groups III and IV dopants, as well as magnetic transition metal atoms such as Mn, Fe, Co, V, Nb, and Ta. By using density functional theory over a 5 × 5 atomic cell, we identify the most promising element candidates for p-doping of MoS2. Specifically, we found VB group impurity elements, such as Ta, substituting Mo to achieve negative formation energy values with impurity states all sitting at less than 0.1 eV from the valence band maximum (VBM), making them the optimal p-type dopant candidates. Moreover, our 5 × 5 cell model shows that B, a group III element, can induce impurity states very close to the VBM with a low formation energy around 0.2 eV, which has not been reported previously. Among the magnetic impurities such as Mn, Fe, and Co with 1, 2, and 3 magnetic moments/atom, respectively, Mn has the lowest formation energy, the most localized spin distribution, and the nearest impurity level to the conduction band among those elements. Additionally, impurity levels and Fermi level for the above three elements are closer to the conduction band than the previous work (PCCP 16:8990-8996, 2014) which shows the possibility of n-type doping by Mn, thanks to our 5 × 5 cell model.

No MeSH data available.