graphene and hexagonal boron nitride substrates. R. Du; K. Kang; ... The photoluminescence (PL) mapping from monolayer MoS2 grown on hBN shows ...
Epitaxial growth of transition metal dichalcogenide monolayers on graphene and hexagonal boron nitride substrates R. Du; K. Kang; K. Godin; S. Chen; X. Wang and E. H. Yang Department of Mechanical Engineering
1. Motivation •
• •
Heterostructures made by stacking different two‐ dimensional (2D) materials enable advanced electronics and optoelectronics. Goal: Chemical vapor deposition (CVD) growth of TMDs on hBN and graphene. Result: Epitaxial CVD growth of TMDs on hBN and graphene exhibiting in‐phase formation of heterostructures without a post‐transfer process.
MRS 2016
• The photoluminescence (PL) mapping from monolayer MoS2 grown on hBN shows uniformity of the PL peak location at 1.88 eV. • PL peak of CVD grown MoS2 on hBN is 1.88eV, comparable to free‐standing MoS2 flakes (1.90 eV), implying that our MoS2 is less electrically disturbed than CVD grown MoS2 on SiO2 substrates [1]. • The PL full width half maximum (FWHM) of the samples is ~ 50 meV, showing the high crystallinity of grown MoS2 and the clean interface realized between MoS2 and hBN [2].
4. WS2 on Graphene 2. Growth Scheme
2D
WS2
Direct CVD growth of WS2 on graphene
G
Electron beam evaporation UV Light
5nm WO3 Si/SiO2 substrate Ar, H2
Si/SiO2 substrate
WO3 Si/SiO2 substrate with CVD‐graphene
graphene
Sulfur
Ar, H2 SiO2
850Ԩ
WS2 on Graphene
Direct CVD growth of MoS2 on hBN Electron beam evaporation 5nm MoO3 Si/SiO2 substrate Ar
MoO3
Sulfur
Ar WS2 on SiO2
Si/SiO2 substrate with exfoliated hBN flakes
750Ԩ
Graphene
• False colored SEM image shows large coverage of WS2 growth on graphene
3. MoS2 on hBN
• SAED (selected area electron diffraction) shows in‐phase growth (i.e. aligned crystal orientation) of WS2 on graphene
5. Conclusion
E
C
Direct CVD growth enables the formation of TMDs monolayers onto different 2D layers without a layer‐transfer process.
1.88 eV A
TMD monolayers can be grown directly on graphene and hBN with high surface coverage.
D B
MoS2 monolayers grown on hBN have a consistent PL peak location, comparable to free‐standing MoS2 flakes. 1.88 eV 1.81 eV
MoS2 monolayers grown on hBN show narrow PL FWHM, implying high crystallinity of grown MoS2 and the clean interface realized between MoS2 and hBN.
6. References [1] Yan, Aiming, et al. "Direct growth of single‐and few‐layer MoS2 on h‐BN with preferred relative rotation angles." Nano letters 15.10 (2015): 6324‐6331. [2] Okada, Mitsuhiro, et al. "Direct chemical vapor deposition growth of WS2 atomic layers on hexagonal boron nitride." ACS nano 8.8 (2014): 8273‐8277.