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Spatiotemporal Imaging of Thickness-Induced Band Bending Junctions

Wong, Joeson and Davoyan, Artur R. and Liao, Bolin and Krayev, Andrey and Jo, Kiyoung and Rotenberg, Eli and Bostwick, Aaron and Jozwiak, Chris and Jariwala, Deep and Zewail, Ahmed H. and Atwater, Harry A. (2021) Spatiotemporal Imaging of Thickness-Induced Band Bending Junctions. . (Unpublished)

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Van der Waals materials exhibit naturally passivated surfaces and can form versatile heterostructures, enabling observation of carrier transport mechanisms not seen in three-dimensional materials. Here we report observation of a "band bending junction", a new type of semiconductor homojunction whose surface potential landscape depends solely on a difference in thickness between the two semiconductor regions atop a buried heterojunction interface. Using MoS₂ on Au to form a buried heterojunction interface, we find that lateral surface potential differences can arise in MoS₂ from the local extent of vertical band bending in thin and thick MoS₂ regions. Using scanning ultrafast electron microscopy, we examine the spatiotemporal dynamics of photogenerated charge carriers and find that lateral carrier separation is enabled by a band bending junction, which is confirmed with semiconductor transport simulations. Band bending junctions may therefore enable new electronic and optoelectronic devices in Van der Waals materials that rely on thickness variations rather than doping to separate charge carriers.

Item Type:Report or Paper (Discussion Paper)
Related URLs:
URLURL TypeDescription Paper
Wong, Joeson0000-0002-6304-7602
Davoyan, Artur R.0000-0002-4662-1158
Liao, Bolin0000-0002-0898-0803
Jo, Kiyoung0000-0003-4587-234X
Rotenberg, Eli0000-0002-3979-8844
Bostwick, Aaron0000-0002-9008-2980
Jozwiak, Chris0000-0002-0980-3753
Jariwala, Deep0000-0002-3570-8768
Atwater, Harry A.0000-0001-9435-0201
Additional Information:Attribution 4.0 International (CC BY 4.0). This work was primarily supported by the 'Photonics at Thermodynamic Limits' Energy Frontier Research Center funded by the U.S. Department of Energy, Office of Science, Office of Basic Energy Sciences under Award Number DE-SC0019140, which supported the sample fabrication, experimental measurements, data analysis, and simulations. J.W acknowledges additional support from the National Science Foundation Graduate Research Fellowship under Grant No. 1144469. Data analysis by A.R.D acknowledges support from UCLA Council on Research Faculty Research Grant. Data analysis by B. L acknowledges support for this work from the U.S. Army Research Office under the award number W911NF-19-1-0060. Additional Kelvin probe force microscopy measurements and data analysis, performed by D.J and K.J, acknowledge support for this work by the U.S. Army Research Office under contract number W911NF-19-1-0109. The work at Penn was carried out at the Singh Center for Nanotechnology which is supported by the National Science Foundation (NSF) National Nanotechnology Coordinated Infrastructure Program grant NNCI-1542153. This research used resources of the Advanced Light Source, a U.S. DOE Office of Science User Facility under contract no. DE-AC02-05CH11231. Author Contributions: J.W, A.R.D, D.J, and H.A.A developed the main ideas. J.W, A.R.D, and D.J fabricated the samples. B.L performed SUEM measurements, developed in the lab of A.Z. A.K and K.J performed the Kelvin Probe measurements. J.W performed ARPES measurements with support from D.J, E.R, A.B., and C.J. J.W performed both the time-domain and steady-state simulations with assistance from A.R.D. H.A.A supervised over all the data analysis. All authors contributed to the discussion and interpretation of results, as well as the presentation and preparation of the manuscript. The authors declare no competing financial interests.
Funding AgencyGrant Number
Department of Energy (DOE)DE-SC0019140
NSF Graduate Research FellowshipDGE-1144469
Army Research Office (ARO)W911NF-19-1-0060
Army Research Office (ARO)W911NF-19-1-0109
Department of Energy (DOE)DE-AC02-05CH11231
Subject Keywords:Band bending, Two-Dimensional, Semiconductors, Photovoltaics, Ultrafast, Spatiotemporal Imaging
Record Number:CaltechAUTHORS:20210322-102902659
Persistent URL:
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:108506
Deposited By: Tony Diaz
Deposited On:23 Mar 2021 15:43
Last Modified:23 Mar 2021 15:43

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