DOE PAGES title logo U.S. Department of Energy
Office of Scientific and Technical Information

Title: Experimental Determination of the Ionization Energies of MoSe2, WS2, and MoS2 on SiO2 Using Photoemission Electron Microscopy

Abstract

Here, the values of the ionization energies of transition metal dichalcogenides (TMDs) are needed to assess their potential usefulness in semiconductor heterojunctions for high-performance optoelectronics. Here, we report on the systematic determination of ionization energies for three prototypical TMD monolayers (MoSe2, WS2, and MoS2) on SiO2 using photoemission electron microscopy with deep ultraviolet illumination. The ionization energy displays a progressive decrease from MoS2, to WS2, to MoSe2, in agreement with predictions of density functional theory calculations. Combined with the measured energy positions of the valence band edge at the Brillouin zone center, we deduce that, in the absence of interlayer coupling, a vertical heterojunction comprising any of the three TMD monolayers would form a staggered (type-II) band alignment. This band alignment could give rise to long-lived interlayer excitons that are potentially useful for valleytronics or efficient electron–hole separation in photovoltaics.

Authors:
 [1];  [2];  [1];  [1];  [3];  [2];  [2];  [1]; ORCiD logo [3]; ORCiD logo [2]
  1. Rice Univ., Houston, TX (United States)
  2. Sandia National Lab. (SNL-NM), Albuquerque, NM (United States)
  3. Los Alamos National Lab. (LANL), Los Alamos, NM (United States)
Publication Date:
Research Org.:
Sandia National Lab. (SNL-NM), Albuquerque, NM (United States)
Sponsoring Org.:
USDOE Office of Energy Efficiency and Renewable Energy (EERE)
OSTI Identifier:
1399563
Report Number(s):
SAND-2017-8462J
Journal ID: ISSN 1936-0851; 656074
Grant/Contract Number:  
AC04-94AL85000
Resource Type:
Accepted Manuscript
Journal Name:
ACS Nano
Additional Journal Information:
Journal Volume: 11; Journal Issue: 8; Journal ID: ISSN 1936-0851
Publisher:
American Chemical Society (ACS)
Country of Publication:
United States
Language:
English
Subject:
36 MATERIALS SCIENCE; 37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY; band alignment; ionization energy; molybdenum disulfide; molybdenum selenide; photoemission electron microscopy; transition metal dichalcogenide; tungsten disulfide

Citation Formats

Keyshar, Kunttal, Berg, Morgann, Zhang, Xiang, Vajtai, Robert, Gupta, Gautam, Chan, Calvin K., Beechem, Thomas E., Ajayan, Pulickel M., Mohite, Aditya D., and Ohta, Taisuke. Experimental Determination of the Ionization Energies of MoSe2, WS2, and MoS2 on SiO2 Using Photoemission Electron Microscopy. United States: N. p., 2017. Web. doi:10.1021/acsnano.7b03242.
Keyshar, Kunttal, Berg, Morgann, Zhang, Xiang, Vajtai, Robert, Gupta, Gautam, Chan, Calvin K., Beechem, Thomas E., Ajayan, Pulickel M., Mohite, Aditya D., & Ohta, Taisuke. Experimental Determination of the Ionization Energies of MoSe2, WS2, and MoS2 on SiO2 Using Photoemission Electron Microscopy. United States. https://doi.org/10.1021/acsnano.7b03242
Keyshar, Kunttal, Berg, Morgann, Zhang, Xiang, Vajtai, Robert, Gupta, Gautam, Chan, Calvin K., Beechem, Thomas E., Ajayan, Pulickel M., Mohite, Aditya D., and Ohta, Taisuke. Wed . "Experimental Determination of the Ionization Energies of MoSe2, WS2, and MoS2 on SiO2 Using Photoemission Electron Microscopy". United States. https://doi.org/10.1021/acsnano.7b03242. https://www.osti.gov/servlets/purl/1399563.
@article{osti_1399563,
title = {Experimental Determination of the Ionization Energies of MoSe2, WS2, and MoS2 on SiO2 Using Photoemission Electron Microscopy},
author = {Keyshar, Kunttal and Berg, Morgann and Zhang, Xiang and Vajtai, Robert and Gupta, Gautam and Chan, Calvin K. and Beechem, Thomas E. and Ajayan, Pulickel M. and Mohite, Aditya D. and Ohta, Taisuke},
abstractNote = {Here, the values of the ionization energies of transition metal dichalcogenides (TMDs) are needed to assess their potential usefulness in semiconductor heterojunctions for high-performance optoelectronics. Here, we report on the systematic determination of ionization energies for three prototypical TMD monolayers (MoSe2, WS2, and MoS2) on SiO2 using photoemission electron microscopy with deep ultraviolet illumination. The ionization energy displays a progressive decrease from MoS2, to WS2, to MoSe2, in agreement with predictions of density functional theory calculations. Combined with the measured energy positions of the valence band edge at the Brillouin zone center, we deduce that, in the absence of interlayer coupling, a vertical heterojunction comprising any of the three TMD monolayers would form a staggered (type-II) band alignment. This band alignment could give rise to long-lived interlayer excitons that are potentially useful for valleytronics or efficient electron–hole separation in photovoltaics.},
doi = {10.1021/acsnano.7b03242},
journal = {ACS Nano},
number = 8,
volume = 11,
place = {United States},
year = {Wed Jul 19 00:00:00 EDT 2017},
month = {Wed Jul 19 00:00:00 EDT 2017}
}

Journal Article:
Free Publicly Available Full Text
Publisher's Version of Record

Citation Metrics:
Cited by: 57 works
Citation information provided by
Web of Science

Save / Share:

Works referenced in this record:

Van der Waals heterostructures
journal, July 2013

  • Geim, A. K.; Grigorieva, I. V.
  • Nature, Vol. 499, Issue 7459, p. 419-425
  • DOI: 10.1038/nature12385

Coupled Spin and Valley Physics in Monolayers of MoS 2 and Other Group-VI Dichalcogenides
journal, May 2012


Lateral heterojunctions within monolayer MoSe2–WSe2 semiconductors
journal, August 2014

  • Huang, Chunming; Wu, Sanfeng; Sanchez, Ana M.
  • Nature Materials, Vol. 13, Issue 12, p. 1096-1101
  • DOI: 10.1038/nmat4064

The valley Hall effect in MoS2 transistors
journal, June 2014


Integrated Circuits and Logic Operations Based on Single-Layer MoS 2
journal, November 2011

  • Radisavljevic, Branimir; Whitwick, Michael Brian; Kis, Andras
  • ACS Nano, Vol. 5, Issue 12
  • DOI: 10.1021/nn203715c

Integrated Circuits Based on Bilayer MoS2 Transistors
journal, January 2012

  • Wang, Han; Yu, Lili; Lee, Yi-Hsien
  • Nano Letters, Vol. 12, Issue 9, p. 4674-4680
  • DOI: 10.1021/nl302015v

Single-Layer MoS2 Phototransistors
journal, December 2011

  • Yin, Zongyou; Li, Hai; Li, Hong
  • ACS Nano, Vol. 6, Issue 1, p. 74-80
  • DOI: 10.1021/nn2024557

Stable, Single-Layer MX 2 Transition-Metal Oxides and Dichalcogenides in a Honeycomb-Like Structure
journal, April 2012

  • Ataca, C.; Şahin, H.; Ciraci, S.
  • The Journal of Physical Chemistry C, Vol. 116, Issue 16
  • DOI: 10.1021/jp212558p

Electronic Band Structures of Molybdenum and Tungsten Dichalcogenides by the GW Approach
journal, March 2012

  • Jiang, Hong
  • The Journal of Physical Chemistry C, Vol. 116, Issue 14
  • DOI: 10.1021/jp300079d

Band offsets and heterostructures of two-dimensional semiconductors
journal, January 2013

  • Kang, Jun; Tongay, Sefaattin; Zhou, Jian
  • Applied Physics Letters, Vol. 102, Issue 1
  • DOI: 10.1063/1.4774090

Band alignment of two-dimensional transition metal dichalcogenides: Application in tunnel field effect transistors
journal, July 2013

  • Gong, Cheng; Zhang, Hengji; Wang, Weihua
  • Applied Physics Letters, Vol. 103, Issue 5
  • DOI: 10.1063/1.4817409

Computational 2D Materials Database: Electronic Structure of Transition-Metal Dichalcogenides and Oxides
journal, June 2015

  • Rasmussen, Filip A.; Thygesen, Kristian S.
  • The Journal of Physical Chemistry C, Vol. 119, Issue 23
  • DOI: 10.1021/acs.jpcc.5b02950

Band alignment of two-dimensional semiconductors for designing heterostructures with momentum space matching
journal, July 2016


Strong interlayer coupling in van der Waals heterostructures built from single-layer chalcogenides
journal, April 2014

  • Fang, H.; Battaglia, C.; Carraro, C.
  • Proceedings of the National Academy of Sciences, Vol. 111, Issue 17
  • DOI: 10.1073/pnas.1405435111

Determination of band alignment in the single-layer MoS2/WSe2 heterojunction
journal, July 2015

  • Chiu, Ming-Hui; Zhang, Chendong; Shiu, Hung-Wei
  • Nature Communications, Vol. 6, Issue 1
  • DOI: 10.1038/ncomms8666

Determination of band offsets, hybridization, and exciton binding in 2D semiconductor heterostructures
journal, February 2017

  • Wilson, Neil R.; Nguyen, Paul V.; Seyler, Kyle
  • Science Advances, Vol. 3, Issue 2
  • DOI: 10.1126/sciadv.1601832

Spatially resolved, energy-filtered imaging of core level and valence band photoemission of highly p and n doped silicon patterns
journal, July 2009


Open Counter for Low Energy Electron Detection
journal, January 1985


Size-Dependent Valence and Conduction Band-Edge Energies of Semiconductor Nanocrystals
journal, June 2011

  • Jasieniak, Jacek; Califano, Marco; Watkins, Scott E.
  • ACS Nano, Vol. 5, Issue 7
  • DOI: 10.1021/nn201681s

Atomically Thin MoS2 A New Direct-Gap Semiconductor
journal, September 2010


Surface potential and interlayer screening effects of few-layer MoS 2 nanoflakes
journal, April 2013

  • Li, Yang; Xu, Cheng-Yan; Zhen, Liang
  • Applied Physics Letters, Vol. 102, Issue 14
  • DOI: 10.1063/1.4801844

Electric-Field Screening in Atomically Thin Layers of MoS 2 : the Role of Interlayer Coupling
journal, November 2012

  • Castellanos-Gomez, Andres; Cappelluti, Emmanuele; Roldán, Rafael
  • Advanced Materials, Vol. 25, Issue 6
  • DOI: 10.1002/adma.201203731

Vertical and in-plane heterostructures from WS2/MoS2 monolayers
journal, September 2014

  • Gong, Yongji; Lin, Junhao; Wang, Xingli
  • Nature Materials, Vol. 13, Issue 12, p. 1135-1142
  • DOI: 10.1038/nmat4091

Stacking-Dependent Interlayer Coupling in Trilayer MoS 2 with Broken Inversion Symmetry
journal, November 2015


Photoemission studies of layered transition-metal dichalcogenides: Mo S 2
journal, December 1977


Van der Waals Epitaxy of Two-Dimensional MoS 2 –Graphene Heterostructures in Ultrahigh Vacuum
journal, May 2015


Method for the analysis of nonselective spectra of optically stimulated electron emission from irradiated dielectrics
journal, August 2005

  • Zatsepin, A. F.; Biryukov, D. Yu.; Kortov, V. S.
  • physica status solidi (a), Vol. 202, Issue 10
  • DOI: 10.1002/pssa.200420054

Photoemission and luminescence properties of quartz glass implanted with Cu+ ions
journal, June 2008

  • Zatsepin, A. F.; Kortov, V. S.; Gavrilov, N. V.
  • Journal of Surface Investigation. X-ray, Synchrotron and Neutron Techniques, Vol. 2, Issue 3
  • DOI: 10.1134/S1027451008030233

Operando x-ray photoelectron emission microscopy for studying forward and reverse biased silicon p-n junctions
journal, May 2016

  • Barrett, N.; Gottlob, D. M.; Mathieu, C.
  • Review of Scientific Instruments, Vol. 87, Issue 5
  • DOI: 10.1063/1.4948597

Near-unity photoluminescence quantum yield in MoS2
journal, November 2015


Controllable Growth of Large–Size Crystalline MoS2 and Resist-Free Transfer Assisted with a Cu Thin Film
journal, December 2015

  • Lin, Ziyuan; Zhao, Yuda; Zhou, Changjian
  • Scientific Reports, Vol. 5, Issue 1
  • DOI: 10.1038/srep18596

Giant spin-orbit-induced spin splitting in two-dimensional transition-metal dichalcogenide semiconductors
journal, October 2011


Tunable band gaps in bilayer transition-metal dichalcogenides
journal, November 2011


Efficient work-function engineering of solution-processed MoS2 thin-films for novel hole and electron transport layers leading to high-performance polymer solar cells
journal, January 2013

  • Yun, Jin-Mun; Noh, Yong-Jin; Yeo, Jun-Seok
  • Journal of Materials Chemistry C, Vol. 1, Issue 24
  • DOI: 10.1039/c3tc30504j

Effect of contaminations and surface preparation on the work function of single layer MoS 2
journal, January 2014

  • Ochedowski, Oliver; Marinov, Kolyo; Scheuschner, Nils
  • Beilstein Journal of Nanotechnology, Vol. 5
  • DOI: 10.3762/bjnano.5.32

Direct and Indirect Excitation Processes in Photoelectric Emission from Silicon
journal, July 1962


Detailed photocurrent spectroscopy of the semiconducting group VIB transition metal dichalcogenides
journal, February 1982

  • Kam, K. K.; Parkinson, B. A.
  • The Journal of Physical Chemistry, Vol. 86, Issue 4
  • DOI: 10.1021/j100393a010

Identification of Active Edge Sites for Electrochemical H2 Evolution from MoS2 Nanocatalysts
journal, July 2007

  • Jaramillo, T. F.; Jorgensen, K. P.; Bonde, J.
  • Science, Vol. 317, Issue 5834, p. 100-102
  • DOI: 10.1126/science.1141483

Efficient hydrogen evolution in transition metal dichalcogenides via a simple one-step hydrazine reaction
journal, June 2016

  • Cummins, Dustin R.; Martinez, Ulises; Sherehiy, Andriy
  • Nature Communications, Vol. 7, Issue 1
  • DOI: 10.1038/ncomms11857

Revealing Defect-State Photoluminescence in Monolayer WS 2 by Cryogenic Laser Processing
journal, May 2016


Defect-Dominated Doping and Contact Resistance in MoS 2
journal, February 2014

  • McDonnell, Stephen; Addou, Rafik; Buie, Creighton
  • ACS Nano, Vol. 8, Issue 3
  • DOI: 10.1021/nn500044q

The role of electronic coupling between substrate and 2D MoS2 nanosheets in electrocatalytic production of hydrogen
journal, June 2016

  • Voiry, Damien; Fullon, Raymond; Yang, Jieun
  • Nature Materials, Vol. 15, Issue 9
  • DOI: 10.1038/nmat4660

Bandgap, Mid-Gap States, and Gating Effects in MoS 2
journal, July 2014

  • Lu, Chih-Pin; Li, Guohong; Mao, Jinhai
  • Nano Letters, Vol. 14, Issue 8
  • DOI: 10.1021/nl501659n

Universal energy-level alignment of molecules on metal oxides
journal, November 2011

  • Greiner, Mark T.; Helander, Michael G.; Tang, Wing-Man
  • Nature Materials, Vol. 11, Issue 1
  • DOI: 10.1038/nmat3159

Fluorescence Concentric Triangles: A Case of Chemical Heterogeneity in WS 2 Atomic Monolayer
journal, August 2016


Microsteganography on WS 2 Monolayers Tailored by Direct Laser Painting
journal, January 2017


Nonblinking, Intense Two-Dimensional Light Emitter: Monolayer WS 2 Triangles
journal, November 2013

  • Peimyoo, Namphung; Shang, Jingzhi; Cong, Chunxiao
  • ACS Nano, Vol. 7, Issue 12
  • DOI: 10.1021/nn4046002

The Effect of Preparation Conditions on Raman and Photoluminescence of Monolayer WS2
journal, October 2016

  • McCreary, Kathleen M.; Hanbicki, Aubrey T.; Singh, Simranjeet
  • Scientific Reports, Vol. 6, Issue 1
  • DOI: 10.1038/srep35154

Distinct photoluminescence and Raman spectroscopy signatures for identifying highly crystalline WS 2 monolayers produced by different growth methods
journal, March 2016

  • McCreary, Amber; Berkdemir, Ayse; Wang, Junjie
  • Journal of Materials Research, Vol. 31, Issue 7
  • DOI: 10.1557/jmr.2016.47

One-Dimensional Metallic Edge States in MoS 2
journal, October 2001


Direct Imaging of Band Profile in Single Layer MoS 2 on Graphite: Quasiparticle Energy Gap, Metallic Edge States, and Edge Band Bending
journal, April 2014

  • Zhang, Chendong; Johnson, Amber; Hsu, Chang-Lung
  • Nano Letters, Vol. 14, Issue 5
  • DOI: 10.1021/nl501133c

Chemical Vapor Deposition Growth of Crystalline Monolayer MoSe2
journal, April 2014

  • Wang, Xingli; Gong, Yongji; Shi, Gang
  • ACS Nano, Vol. 8, Issue 5, p. 5125-5131
  • DOI: 10.1021/nn501175k

Controlled Growth of High-Quality Monolayer WS 2 Layers on Sapphire and Imaging Its Grain Boundary
journal, September 2013

  • Zhang, Yu; Zhang, Yanfeng; Ji, Qingqing
  • ACS Nano, Vol. 7, Issue 10
  • DOI: 10.1021/nn403454e

Chemical Vapor Deposition Synthesized Atomically Thin Molybdenum Disulfide with Optoelectronic-Grade Crystalline Quality
journal, August 2015


The origin of contrast in the imaging of doped areas in silicon by slow electrons
journal, November 2006

  • Frank, Luděk; Müllerová, Ilona; Valdaitsev, Dimitrii A.
  • Journal of Applied Physics, Vol. 100, Issue 9
  • DOI: 10.1063/1.2364044

Works referencing / citing this record:

Interlayer exciton dynamics in van der Waals heterostructures
journal, February 2019

  • Ovesen, Simon; Brem, Samuel; Linderälv, Christopher
  • Communications Physics, Vol. 2, Issue 1
  • DOI: 10.1038/s42005-019-0122-z

Composition-induced type I and direct bandgap transition metal dichalcogenides alloy vertical heterojunctions
journal, January 2020

  • Zhou, Songsong; Ning, Jinliang; Sun, Jianwei
  • Nanoscale, Vol. 12, Issue 1
  • DOI: 10.1039/c9nr08345f

Theory of exciton dynamics in time-resolved ARPES: Intra- and intervalley scattering in two-dimensional semiconductors
journal, November 2019


Insertion of an ultrathin Al 2 O 3 interfacial layer for Schottky barrier height reduction in WS 2 field-effect transistors
journal, January 2019

  • Zheng, Shan; Lu, Haichang; Liu, Huan
  • Nanoscale, Vol. 11, Issue 11
  • DOI: 10.1039/c8nr07812b

Imaging Atomically Thin Semiconductors Beneath Dielectrics via Deep Ultraviolet Photoemission Electron Microscopy
journal, December 2019


A new metal transfer process for van der Waals contacts to vertical Schottky-junction transition metal dichalcogenide photovoltaics
journal, December 2019

  • Went, Cora M.; Wong, Joeson; Jahelka, Phillip R.
  • Science Advances, Vol. 5, Issue 12
  • DOI: 10.1126/sciadv.aax6061

Work Function Variations in Twisted Graphene Layers
journal, January 2018


Engineering Ultrafast Carrier Dynamics at the Graphene/GaAs Interface by Bulk Doping Level
journal, June 2019

  • Yang, Jinghuan; Sun, Quan; Liu, Wei
  • Advanced Optical Materials, Vol. 7, Issue 19
  • DOI: 10.1002/adom.201900580

Successes and Issues in the Growth of Moad and MoSe2 on Ag(111) by the E-ALD Method
journal, January 2019

  • Vizza, Martina; Giaccherini, Andrea; Giurlani, Walter
  • Metals, Vol. 9, Issue 2
  • DOI: 10.3390/met9020122

Simple vertex correction improves GW band energies of bulk and two-dimensional crystals
text, January 2017