As the channel lengths of electronic devices are scaled down to the nanometer range, the conventional methods to evaluate charge-carrier mobility approach a technical limit that is imposed by interfering effects of the electrode and forcing field. In this study, we demonstrate that electron spectroscopy provides additional (yet hidden) information on unipolar charge transport, which is free from conventional problems. We demonstrate that the estimated effective diffusion current through the target sample allows the measurement that is precise enough (10−4 cm2/V s) to obtain the mobility of electrons μelectron and holes μhole in nanolength organic channels. Using this method, we show how μelectron and μhole are correlated with the local structural order of poly(3-hexylthiophene) at the nanoscale. This method enables in situ charge-resolved observations of μelectron and μhole by eliminating the need for electrode and forcing field and will help to expand our understanding of charge conduction in nanoscale materials.
REFERENCES
1.
H. H.
Choi
, K.
Cho
, C. D.
Frisbie
, H.
Sirringhaus
, and V.
Podzorov
, “Critical assessment of charge mobility extraction in FETs
,” Nat. Mater.
17
, 2
–7
(2018
). 2.
H.
Li
, J.-K.
Huang
, Y.
Shi
, and L.-J.
Li
, “Toward the growth of high mobility 2D transition metal dichalcogenide semiconductors
,” Adv. Mater. Interfaces
6
, 1900220
(2019
). 3.
D.
Shin
, Y.
Lee
, M.
Sasaki
, Y. H.
Jeong
, F.
Weickert
, J. B.
Betts
, H.-J.
Kim
, K.-S.
Kim
, and J.
Kim
, “Violation of Ohm's law in a weyl metal
,” Nat. Mater.
16
, 1096
–1099
(2017
). 4.
D. K.
Sang
, H.
Wang
, M.
Qiu
, R.
Cao
, Z.
Guo
, J.
Zhao
, Y.
Li
, Q.
Xiao
, D.
Fan
, and H.
Zhang
, “Two dimensional β-InSe with layer-dependent properties: Band alignment, work function and optical properties
,” Nanomaterials
9
, 82
(2019
). 5.
A. M.
Ballantyne
, L.
Chen
, J.
Dane
, T.
Hammant
, F. M.
Braun
, M.
Heeney
, W.
Duffy
, I.
McCulloch
, D. D. C.
Bradley
, and J.
Nelson
, “The effect of poly(3-hexylthiophene) molecular weight on charge transport and the performance of polymer:fullerene solar cells
,” Adv. Funct. Mater.
18
, 2373
–2380
(2008
). 6.
Y.
Guo
, X.
Wang
, B.
Miao
, Y.
Li
, W.
Yao
, Y.
Xie
, J.
Li
, D.
Wu
, and R.
Pei
, “An AuNPs-functionalized AlGaN/GaN high electron mobility transistor sensor for ultrasensitive detection of TNT
,” RSC Adv.
5
, 98724
–98729
(2015
). 7.
T.
Bura
, N.
Leclerc
, S.
Fall
, P.
Leveque
, T.
Heiser
, P.
Retailleau
, S.
Rihn
, A.
Mirloup
, and R.
Ziessel
, “High-performance solution-processed solar cells and ambipolar behavior in organic field-effect transistors with thienyl-BODIPY scaffoldings
,” J. Am. Chem. Soc.
134
, 17404
–17407
(2012
). 8.
J.
Zaumseil
and H.
Sirringhaus
, “Electron and ambipolar transport in organic field-effect transistors
,” Chem. Rev.
107
, 1296
–1323
(2007
). 9.
E. J.
Meijer
, D. M.
de Leeuw
, S.
Setayesh
, E.
van Veenendaal
, B.-H.
Huisman
, P. W. M.
Blom
, J. C.
Hummelen
, U.
Scherf
, and T. M.
Klapwijk
, “Solution-processed ambipolar organic field-effect transistors and inverters
,” Nat. Mater.
2
, 678
–682
(2003
). 10.
S.
Bange
, M.
Schubert
, and D.
Neher
, “Charge mobility determination by current extraction under linear increasing voltages: Case of nonequilibrium charges and field-dependent mobilities
,” Phys. Rev. B
81
, 035209
(2010
). 11.
K.
Ihm
, S.
Chung
, T.-H.
Kang
, and S.-W.
Cheong
, “Early stages of collapsing pentacene crystal by Au
,” Appl. Phys. Lett.
93
, 141906
(2008
). 12.
J. H.
Cho
, D. H.
Kim
, Y.
Jang
, W. H.
Lee
, K.
Ihm
, J.-H.
Han
, S.
Chung
, and K.
Cho
, “Effects of metal penetration into organic semiconductors on the electrical properties of organic thin film transistors
,” Appl. Phys. Lett.
89
, 132101
(2006
). 13.
A. K. A.
Lu
, G.
Pourtois
, T.
Agarwal
, A.
Afzalian
, I. P.
Radu
, and M.
Houssa
, “Origin of the performances degradation of two-dimensional-based metal-oxide-semiconductor field effect transistors in the sub-10 nm regime: A first-principles study
,” Appl. Phys. Lett.
108
, 043504
(2016
). 14.
G.-S.
Kim
, S.-H.
Kim
, J.
Park
, K. H.
Han
, J.
Kim
, and H.-Y.
Yu
, “Schottky barrier height engineering for electrical contacts of multilayered MoS2 transistors with reduction of metal-induced gap states
,” ACS Nano
12
, 6292
–6300
(2018
). 15.
K.
Sotthewes
, R.
van Bremen
, E.
Dollekamp
, T.
Boulogne
, K.
Nowakowski
, D.
Kas
, H. J. W.
Zandvliet
, and P.
Bampoulis
, “Universal fermi-level pinning in transition-metal dichalcogenides
,” J. Phys. Chem. C
123
, 5411
–5420
(2019
). 16.
Y.
Wang
, S.
Liu
, Q.
Li
, R.
Quhe
, C.
Yang
, Y.
Guo
, X.
Zhang
, Y.
Pan
, J.
Li
, H.
Zhang
, L.
Xu
, B.
Shi
, H.
Tang
, Y.
Li
, J.
Yang
, Z.
Zhang
, L.
Xiao
, F.
Pan
, and J.
Lu
, “Schottky barrier heights in two-dimensional field-effect transistors: From theory to experiment
,” Rep. Prog. Phys.
84
, 056501
(2021
). 17.
D. K.
Schroder
, Semiconductor Materials and Device Characterization
(John Wiley & Sons
, 2006
), pp. 465
–480
.18.
Y.
Leng
, Materials Characterization: Introduction to Microscopic and Spectroscopic Methods
(John Wiley & Sons
, 2013
), pp. 191
–192
, 221–224.19.
Q. M.
Ramasse
, C. R.
Seabourne
, D.-M.
Kepaptsoglou
, R.
Zan
, U.
Bangert
, and A. J.
Scott
, “Probing the bonding and electronic structure of single atom dopants in graphene with electron energy loss spectroscopy
,” Nano Lett.
13
, 4989
–4995
(2013
). 20.
S. A.
Komolov
and L. T.
Chadderton
, “Total current spectroscopy
,” Surf. Sci.
90
, 359
–380
(1979
). 21.
K.
Ihm
, M.
Yang
, Y.
Kim
, and J.
Lee
, “Apparatus for electrodeless measurement of electron mobility in nano materials,” U.S. patent 11,243,178 (February 8, 2022).22.
M. P.
Seah
, “Slow electron scattering from metal I. The emission of true secondary electrons
,” Surf. Sci.
17
, 132
–160
(1969
). 23.
H. D.
Hagstrum
, “Theory of auger ejection of electrons from metals by ions
,” Phys. Rev.
96
, 336
–365
(1954
). 24.
H. S.
Uhm
, G. C.
Kwon
, and E. H.
Choi
, “Measurement of valence band structure in boron-zinc-oxide films by making use of ion beams
,” Appl. Phys. Lett.
99
, 261502
(2011
). 25.
Y.
Xue
, S.
Datta
, S.
Hong
, R.
Reifenberger
, J.
Henderson
, and C.
Kubiak
, “Negative differential resistance in the scanning-tunneling spectroscopy of organic molecules
,” Phys. Rev. B
59
, R7852
–R7855
(1999
). 26.
M. G.
Helander
, M. T.
Greiner
, Z. B.
Wang
, and Z. H.
Lu
, “Pitfalls in measuring work function using photoelectron spectroscopy
,” Appl. Surf. Sci.
256
, 2602
–2605
(2010
). 27.
T.-H.
Liu
, J.
Zhou
, B.
Liao
, D. J.
Singh
, and G.
Chen
, “First-principles mode-by-mode analysis for electron-phonon scattering channels and mean free path spectra in GaAs
,” Phys. Rev. B
95
, 075206
(2017
). 28.
N. W.
Ashcroft
and N.
David Mermin
, Solid State Physics
(Saunders College Publishing
, 1976
), p. 563
.29.
K.
Martens
, J. W.
Jeong
, N.
Aetukuri
, C.
Rettner
, N.
Shukla
, E.
Freeman
, D. N.
Esfahani
, F. M.
Peeters
, T.
Topuria
, P. M.
Rice
, A.
Volodin
, B.
Douhard
, W.
Vandervorst
, M. G.
Samant
, S.
Datta
, and S. S. P.
Parkin
, “Field effect and strongly localized carriers in the metal-insulator transition material VO2
,” Phys. Rev. Lett.
115
, 196401
(2015
). 30.
T.
Yamin
, Y. M.
Strelniker
, and A.
Sharoni
, “High resolution Hall measurements across the VO2 metal-insulator transition reveal impact of spatial phase separation
,” Sci. Rep.
6
, 19496
(2016
). 31.
J.
Kang
, W.
Liu
, D.
Sarkar
, D.
Jena
, and K.
Banerjee
, “Computational study of metal contacts to monolayer transition-metal dichalcogenide semiconductors
,” Phys. Rev. X
4
, 031005
(2014
). 32.
H.
Mehrer
, Diffusion in Solids
(Springer-Verlag
, Berlin
, 2007
), pp. 37
–40
.33.
A.
Einstein
, “Über die von der molekularkinetischen theorie der wärme geforderte bewegung von in ruhenden flüssigkeiten suspendierten teilchen
,” Ann. Phys.
322
, 549
–560
(1905
). 34.
K. M.
Powell
and H. P.
Yoon
, “Depth-dependent EBIC microscopy of radial-junction Si micropillar arrays
,” Appl. Microsc.
50
, 17
(2020
). 35.
H. J.
Leamy
, “Charge collection scanning electron microscopy
,” J. Appl. Phys.
53
, R51
–R80
(1982
). 36.
R.
Noriega
, J.
Rivnay
, K.
Vandewal
, F. P. V.
Koch
, N.
Stingelin
, P.
Smith
, M. F.
Toney
, and A.
Salleo
, “A general relationship between disorder, aggregation and charge transport in conjugated polymers
,” Nat. Mater.
12
, 1038
–1044
(2013
). 37.
D.
Choi
, S.
Jin
, Y.
Lee
, S. H.
Kim
, D. S.
Chung
, K.
Hong
, C.
Yang
, J.
Jung
, J. K.
Kim
, M.
Ree
, and C. E.
Park
, “Direct observation of interfacial morphology in poly(3-hexylthiophene) transistors: Relationship between grain boundary and field-effect mobility
,” ACS Appl. Mater. Interfaces
2
, 48
–53
(2010
). 38.
M. F.
Ahmed
and I. A.
Hummelgen
, “Determination of electron and hole mobility in poly(3-hexylthiophene) using space-charge-limited-current measurements
,” Int. J. Electroactive Mater.
1
, 60
–63 (2013
).39.
A. J.
Mozer
, N. S.
Sariciftci
, A.
Pivrikas
, R.
Österbacka
, G.
Juška
, L.
Brassat
, and H.
Bässler
, “Charge carrier mobility in regioregular poly(3-hexylthiophene) probed by transient conductivity techniques: A comparative study
,” Phys. Rev. B
71
, 035214
(2005
). 40.
S. A.
Choulis
, Y.
Kim
, J.
Nelson
, D. D. C.
Bradley
, M.
Giles
, M.
Shkunov
, and I.
McCulloch
, “High ambipolar and balanced carrier mobility in regioregular poly(3-hexylthiophene)
,” Appl. Phys. Lett.
85
, 3890
–3892
(2004
). 41.
L.
Janasz
, D.
Chlebosz
, M.
Gradzka
, W.
Zajaczkowski
, T.
Marszalek
, K.
Müllen
, J.
Ulanski
, A.
Kiersnowski
, and W.
Pisula
, “Improved charge carrier transport in ultrathin poly(3-hexylthiophene) films via solution aggregation
,” J. Mater. Chem. C
4
, 11488
–11498
(2016
). 42.
J. L.
Brédas
, J. P.
Calbert
, D. A.
da Silva Filho
, and J.
Cornil
, “Organic semiconductors: A theoretical characterization of the basic parameters governing charge transport
,” Proc. Natl. Acad. Sci. U.S.A.
99
, 5804
–5809
(2002
). © 2023 Author(s). Published under an exclusive license by AIP Publishing.
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