Abstract
Large-area two-dimensional (2D) heterojunctions are promising building blocks of 2D circuits. Understanding their intriguing electrostatics is pivotal but largely hindered by the lack of direct observations. Here graphene-WS2 heterojunctions are prepared over large areas using a seedless ambient-pressure chemical vapor deposition technique. Kelvin probe force microscopy, photoluminescence spectroscopy, and scanning tunneling microscopy characterize the doping in graphene-WS2 heterojunctions as-grown on sapphire and transferred to SiO2 with and without thermal annealing. Both p-n and n-n junctions are observed, and a flat-band condition (zero Schottky barrier height) is found for lightly n-doped WS2, promising low-resistance ohmic contacts. This indicates a more favorable band alignment for graphene-WS2 than has been predicted, likely explaining the low barriers observed in transport experiments on similar heterojunctions. Electrostatic modeling demonstrates that the large depletion width of the graphene-WS2 junction reflects the electrostatics of the one-dimensional junction between two-dimensional materials.
| Original language | English |
|---|---|
| Pages (from-to) | 2785-2793 |
| Number of pages | 9 |
| Journal | ACS Nano |
| Volume | 11 |
| Issue number | 3 |
| DOIs | |
| Publication status | Published - 28 Mar 2017 |
Keywords
- electrostatics
- graphene
- heterostructure
- ohmic contacts
- transition-metal dichalcogenides
Cite this
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Direct observation of 2D electrostatics and ohmic contacts in template-grown graphene/WS2 heterostructures. / Zheng, Changxi; Zhang, Qianhui; Weber, Bent; Ilatikhameneh, Hesameddin; Chen, Fan; Sahasrabudhe, Harshad; Rahman, Rajib; Li, Shiqiang; Chen, Zhenchen; Hellerstedt, Jack; Zhang, Yupeng; Duan, Wen Hui; Bao, Qiaoliang; Fuhrer, Michael S.
In: ACS Nano, Vol. 11, No. 3, 28.03.2017, p. 2785-2793.Research output: Contribution to journal › Article › Research › peer-review
TY - JOUR
T1 - Direct observation of 2D electrostatics and ohmic contacts in template-grown graphene/WS2 heterostructures
AU - Zheng, Changxi
AU - Zhang, Qianhui
AU - Weber, Bent
AU - Ilatikhameneh, Hesameddin
AU - Chen, Fan
AU - Sahasrabudhe, Harshad
AU - Rahman, Rajib
AU - Li, Shiqiang
AU - Chen, Zhenchen
AU - Hellerstedt, Jack
AU - Zhang, Yupeng
AU - Duan, Wen Hui
AU - Bao, Qiaoliang
AU - Fuhrer, Michael S.
PY - 2017/3/28
Y1 - 2017/3/28
N2 - Large-area two-dimensional (2D) heterojunctions are promising building blocks of 2D circuits. Understanding their intriguing electrostatics is pivotal but largely hindered by the lack of direct observations. Here graphene-WS2 heterojunctions are prepared over large areas using a seedless ambient-pressure chemical vapor deposition technique. Kelvin probe force microscopy, photoluminescence spectroscopy, and scanning tunneling microscopy characterize the doping in graphene-WS2 heterojunctions as-grown on sapphire and transferred to SiO2 with and without thermal annealing. Both p-n and n-n junctions are observed, and a flat-band condition (zero Schottky barrier height) is found for lightly n-doped WS2, promising low-resistance ohmic contacts. This indicates a more favorable band alignment for graphene-WS2 than has been predicted, likely explaining the low barriers observed in transport experiments on similar heterojunctions. Electrostatic modeling demonstrates that the large depletion width of the graphene-WS2 junction reflects the electrostatics of the one-dimensional junction between two-dimensional materials.
AB - Large-area two-dimensional (2D) heterojunctions are promising building blocks of 2D circuits. Understanding their intriguing electrostatics is pivotal but largely hindered by the lack of direct observations. Here graphene-WS2 heterojunctions are prepared over large areas using a seedless ambient-pressure chemical vapor deposition technique. Kelvin probe force microscopy, photoluminescence spectroscopy, and scanning tunneling microscopy characterize the doping in graphene-WS2 heterojunctions as-grown on sapphire and transferred to SiO2 with and without thermal annealing. Both p-n and n-n junctions are observed, and a flat-band condition (zero Schottky barrier height) is found for lightly n-doped WS2, promising low-resistance ohmic contacts. This indicates a more favorable band alignment for graphene-WS2 than has been predicted, likely explaining the low barriers observed in transport experiments on similar heterojunctions. Electrostatic modeling demonstrates that the large depletion width of the graphene-WS2 junction reflects the electrostatics of the one-dimensional junction between two-dimensional materials.
KW - electrostatics
KW - graphene
KW - heterostructure
KW - ohmic contacts
KW - transition-metal dichalcogenides
UR - http://www.scopus.com/inward/record.url?scp=85016411153&partnerID=8YFLogxK
U2 - 10.1021/acsnano.6b07832
DO - 10.1021/acsnano.6b07832
M3 - Article
VL - 11
SP - 2785
EP - 2793
JO - ACS Nano
JF - ACS Nano
SN - 1936-0851
IS - 3
ER -