The thermoelectric effects in bulk β-gallium oxide crystals are investigated in this work using the ab initio calculated electron-phonon interactions and semi-classical Boltzmann transport theory. We have taken all major scattering mechanisms into account, namely, polar and non-polar optical phonon, acoustic phonon, and ionized impurity scattering. To accurately account for the polar phonon scattering rate, we take into account the dynamic screening at higher electron densities. An iterative solution of the Boltzmann transport equation is used in order to account for the inelastic and anisotropic nature of polar optical phonon scattering. The thermoelectric transport coefficients, Seebeck coefficient, Peltier coefficient, and electronic thermal conductivity, are calculated for a wide range of temperatures and doping densities. The calculated Seebeck coefficient is compared with the experimentally measured value and found to be in good agreement considering the mobility of the samples. The value of the Seebeck coefficient at 300 K is found to be −341 μVK1, which is high compared to that of the other commonly studied semiconductors. The larger Seebeck coefficient is due to the higher density of states arising from comparatively high electron effective mass.

1.
T. P.
Chow
,
I.
Omura
,
M.
Higashiwaki
,
H.
Kawarada
, and
V.
Pala
, “
Smart power devices and ICs using GaAs and wide and extreme bandgap semiconductors
,”
IEEE Trans. Electron Devices
64
,
856
873
(
2017
).
2.
J. Y.
Tsao
,
S.
Chowdhury
,
M. A.
Hollis
,
D.
Jena
,
N. M.
Johnson
,
K. A.
Jones
,
R. J.
Kaplar
,
S.
Rajan
,
C. G.
Van de Walle
,
E.
Bellotti
,
C. L.
Chua
,
R.
Collazo
,
M. E.
Coltrin
,
J. A.
Cooper
,
K. R.
Evans
,
S.
Graham
,
T. A.
Grotjohn
,
E. R.
Heller
,
M.
Higashiwaki
,
M. S.
Islam
,
P. W.
Juodawlkis
,
M. A.
Khan
,
A. D.
Koehler
,
J. H.
Leach
,
U. K.
Mishra
,
R. J.
Nemanich
,
R. C. N.
Pilawa-Podgurski
,
J. B.
Shealy
,
Z.
Sitar
,
M. J.
Tadjer
,
A. F.
Witulski
,
M.
Wraback
, and
J. A.
Simmons
, “
Ultrawide-bandgap semiconductors: Research opportunities and challenges
,”
Adv. Electron. Mater.
4
,
1600501
(
2018
).
3.
M.
Higashiwaki
and
G. H.
Jessen
, “
Guest editorial: The dawn of gallium oxide microelectronics
,”
Appl. Phys. Lett.
112
,
060401
(
2018
).
4.
K.
Konishi
,
K.
Goto
,
H.
Murakami
,
Y.
Kumagai
,
A.
Kuramata
,
S.
Yamakoshi
, and
M.
Higashiwaki
, “
1-kv vertical (β-Ga2O3) field-plated Schottky barrier diodes
,”
Appl. Phys. Lett.
110
,
103506
(
2017
).
5.
M. H.
Wong
,
K.
Sasaki
,
A.
Kuramata
,
S.
Yamakoshi
, and
M.
Higashiwaki
, “
Field-plated Ga2O3 mosfets with a breakdown voltage of over 750 v
,”
IEEE Electron Device Lett.
37
,
212
215
(
2016
).
6.
K.
Zeng
,
A.
Vaidya
, and
U.
Singisetti
, “
1.85 kv breakdown voltage in lateral field-plated (β-Ga2O3) MOSFETs
,”
IEEE Electron Device Lett.
39
,
1385
1388
(
2018
).
7.
A.
Kuramata
,
K.
Koshi
,
S.
Watanabe
,
Y.
Yamaoka
,
T.
Masui
, and
S.
Yamakoshi
, “
High-quality β-Ga2O3 single crystals grown by edge-defined film-fed growth
,”
Jpn. J. Appl. Phys., Part 1
55
,
1202A2
(
2016
).
8.
Z.
Galazka
,
R.
Uecker
,
D.
Klimm
,
K.
Irmscher
,
M.
Naumann
,
M.
Pietsch
,
A.
Kwasniewski
,
R.
Bertram
,
S.
Ganschow
, and
M.
Bickermann
, “
Scaling-up of bulk β-Ga2O3 single crystals by the Czochralski method
,”
ECS J. Solid State Sci. Technol.
6
,
Q3007
Q3011
(
2017
).
9.
K.
Hoshikawa
,
E.
Ohba
,
T.
Kobayashi
,
J.
Yanagisawa
,
C.
Miyagawa
, and
Y.
Nakamura
, “
Growth of β-Ga2O3 single crystals using vertical Bridgman method in ambient air
,”
J. Cryst. Growth
447
,
36
41
(
2016
).
10.
K.
Sasaki
,
A.
Kuramata
,
T.
Masui
,
E. G.
Víllora
,
K.
Shimamura
, and
S.
Yamakoshi
, “
Device-quality β-Ga2O3 epitaxial films fabricated by ozone molecular beam epitaxy
,”
Appl. Phys. Express
5
,
035502
(
2012
).
11.
M.
Baldini
,
M.
Albrecht
,
A.
Fiedler
,
K.
Irmscher
,
R.
Schewski
, and
G.
Wagner
, “
Siand sndoped homoepitaxial β-Ga2O3 layers grown by MOVPE on (010)-oriented substrates
,”
ECS J. Solid State Sci. Technol.
6
,
Q3040
Q3044
(
2017
).
12.
H.
Murakami
,
K.
Nomura
,
K.
Goto
,
K.
Sasaki
,
K.
Kawara
,
Q. T.
Thieu
,
R.
Togashi
,
Y.
Kumagai
,
M.
Higashiwaki
,
A.
Kuramata
,
S.
Yamakoshi
,
B.
Monemar
, and
A.
Koukitu
, “
Homoepitaxial growth of β-Ga2O3 layers by halide vapor phase epitaxy
,”
Appl. Phys. Express
8
,
015503
(
2015
).
13.
G.
Wagner
,
M.
Baldini
,
D.
Gogova
,
M.
Schmidbauer
,
R.
Schewski
,
M.
Albrecht
,
Z.
Galazka
,
D.
Klimm
, and
R.
Fornari
, “
Homoepitaxial growth of β-Ga2O3 layers by metal-organic vapor phase epitaxy
,”
Phys. Status Solidi A
211
,
27
33
(
2014
).
14.
K.
Ghosh
and
U.
Singisetti
, “
Ab initio calculation of electron-phonon coupling in monoclinic β-Ga2O3 crystal
,”
Appl. Phys. Lett.
109
,
072102
(
2016
).
15.
S.
Poncé
and
F.
Giustino
, “
Structural, electronic, elastic, power, and transport properties of β-Ga2O3 from first principles
,”
Phys. Rev. Res.
2
,
033102
(
2020
).
16.
N.
Ma
,
N.
Tanen
,
A.
Verma
,
Z.
Guo
,
T.
Luo
,
H. G.
Xing
, and
D.
Jena
, “
Intrinsic electron mobility limits in β-Ga2O3
,”
Appl. Phys. Lett.
109
,
212101
(
2016
).
17.
Y.
Kang
,
K.
Krishnaswamy
,
H.
Peelaers
, and
C. G. V.
de Walle
, “
Fundamental limits on the electron mobility of β-Ga2O3
,”
J. Phys.: Condens. Matter
29
,
234001
(
2017
).
18.
M. D.
Santia
,
N.
Tandon
, and
J. D.
Albrecht
, “
Lattice thermal conductivity in β-Ga2O3 from first principles
,”
Appl. Phys. Lett.
107
,
041907
(
2015
).
19.
Z.
Guo
,
A.
Verma
,
X.
Wu
,
F.
Sun
,
A.
Hickman
,
T.
Masui
,
A.
Kuramata
,
M.
Higashiwaki
,
D.
Jena
, and
T.
Luo
, “
Anisotropic thermal conductivity in single crystal β-Ga2O3
,”
Appl. Phys. Lett.
106
,
111909
(
2015
).
20.
N.
Blumenschein
,
M.
Slomski
,
P. P.
Paskov
,
F.
Kaess
,
M. H.
Breckenridge
,
J. F.
Muth
, and
T.
Paskova
, “
Thermal conductivity of bulk and thin film β-Ga2O3 measured by the 3ω technique
,”
Proc. SPIE
10533
,
228
235
(
2018
).
21.
I.
Terasaki
, “
13-introduction to thermoelectricity
,” in
Materials for Energy Conversion Devices
, Woodhead Publishing Series in Electronic and Optical Materials, edited by
C. C.
Sorrell
,
S.
Sugihara
, and
J.
Nowotny
(
Woodhead Publishing
,
2005
), pp.
339
357
.
22.
K. A.
Mengle
and
E.
Kioupakis
,
AIP Advances
9
,
015313
(
2019
).
23.
A.
Parisini
and
R.
Fornari
,
Semicond. Sci. Technol.
31
,
035023
(
2016
).
24.
Z. C.
Zhang
,
Y.
Wu
,
C.
Lu
, et al. “
Electron mobility in β-Ga2O3: An ensemble Monte Carlo study
,”
Appl. Phys. A
124
,
637
(
2018
).
25.
Y.
Zhang
,
Z.
Xia
,
J. F.
Mcglone
,
W.
Sun
,
C.
Joishi
,
A. R.
Arehart
,
S. A.
Ringel
, and
S.
Rajan
, “
Evaluation of low-temperature saturation velocity in β(alxga1x)2o3/ga2o3 modulation-doped field-effect transistors
,”
IEEE Trans. Electron Devices
66
,
1574
1578
(
2019
).
26.
K.
Ghosh
and
U.
Singisetti
, “
Ab initio velocity-field curves in monoclinic β-Ga2O3
,”
J. Appl. Phys.
122
,
035702
(
2017
).
27.
T.
Oishi
,
Y.
Koga
,
K.
Harada
, and
M.
Kasu
, “
High-mobility β-Ga2O3 single crystals grown by edge-defined film-fed growth method and their Schottky barrier diodes with Ni contact
,”
Appl. Phys. Express
8
,
031101
(
2015
).
28.
Y.
Zhang
,
F.
Alema
,
A.
Mauze
,
O. S.
Koksaldi
,
R.
Miller
,
A.
Osinsky
, and
J. S.
Speck
, “
Mocvd grown epitaxial β-Ga2O3 thin film with an electron mobility of 176 cm2 V−1 s−1 at room temperature
,”
APL Mater.
7
,
022506
(
2019
).
29.
K.
Ghosh
and
U.
Singisetti
, “
Electron mobility in monoclinic β-Ga2O3 effect of plasmon-phonon coupling, anisotropy, and confinement
,”
J. Mater. Res.
32
,
4142
4152
(
2017
).
30.
A.
Kumar
,
K.
Ghosh
, and
U.
Singisetti
, “
Low field transport calculation of 2-dimensional electron gas in β-Ga2O3 heterostructures
,”
J. Appl. Phys.
128
,
105703
(
2020
).
31.
J.
Ma
,
F.
Meng
,
D.
Xu
,
R.
Hu
, and
X.
Luo
, “
Electron mobility and mode analysis of scattering for β-Ga2O3 from first principles
,”
J. Phys.: Condens. Matter
32
,
465704
(
2020
).
32.
J.
Boy
,
M.
Handwerg
,
R.
Ahrling
,
R.
Mitdank
,
G.
Wagner
,
Z.
Galazka
, and
S. F.
Fischer
, “
Temperature dependence of the Seebeck coefficient of epitaxial β-Ga2O3 thin films
,”
APL Mater.
7
,
022526
(
2019
).
33.
A.
Kumar
,
S.
Singh
,
B. R.
Tak
,
A.
Patel
,
K.
Asokan
, and
D.
Kanjilal
, “
Wide range temperature-dependent (80–630 K) study of hall effect and the Seebeck coefficient of β-Ga2O3 single crystals
,” arXiv:2008.06015 (
2020
).
34.
P.
Giannozzi
,
O.
Andreussi
,
T.
Brumme
,
O.
Bunau
,
M. B.
Nardelli
,
M.
Calandra
,
R.
Car
,
C.
Cavazzoni
,
D.
Ceresoli
,
M.
Cococcioni
,
N.
Colonna
,
I.
Carnimeo
,
A. D.
Corso
,
S.
de Gironcoli
,
P.
Delugas
,
R. A.
DiStasio
, Jr.
,
A.
Ferretti
,
A.
Floris
,
G.
Fratesi
,
G.
Fugallo
,
R.
Gebauer
,
U.
Gerstmann
,
F.
Giustino
,
T.
Gorni
,
J.
Jia
,
M.
Kawamura
,
H.-Y.
Ko
,
A.
Kokalj
,
E.
Küçükbenli
,
M.
Lazzeri
,
M.
Marsili
,
N.
Marzari
,
F.
Mauri
,
N. L.
Nguyen
,
H.-V.
Nguyen
,
A. O.
de-la Roza
,
L.
Paulatto
,
S.
Poncé
,
D.
Rocca
,
R.
Sabatini
,
B.
Santra
,
M.
Schlipf
,
A. P.
Seitsonen
,
A.
Smogunov
,
I.
Timrov
,
T.
Thonhauser
,
P.
Umari
,
N.
Vast
,
X.
Wu
, and
S.
Baroni
, “
Advanced capabilities for materials modelling with quantum espresso
,”
J. Phys.: Condens. Matter
29
,
465901
(
2017
).
35.
P.
Giannozzi
,
S.
Baroni
,
N.
Bonini
,
M.
Calandra
,
R.
Car
,
C.
Cavazzoni
,
D.
Ceresoli
,
G. L.
Chiarotti
,
M.
Cococcioni
,
I.
Dabo
,
A.
Dal Corso
,
S.
de Gironcoli
,
S.
Fabris
,
G.
Fratesi
,
R.
Gebauer
,
U.
Gerstmann
,
C.
Gougoussis
,
A.
Kokalj
,
M.
Lazzeri
,
L.
Martin-Samos
,
N.
Marzari
,
F.
Mauri
,
R.
Mazzarello
,
S.
Paolini
,
A.
Pasquarello
,
L.
Paulatto
,
C.
Sbraccia
,
S.
Scandolo
,
G.
Sclauzero
,
A. P.
Seitsonen
,
A.
Smogunov
,
P.
Umari
, and
R. M.
Wentzcovitch
, “
Quantum espresso: A modular and open-source software project for quantum simulations of materials
,”
J. Phys.: Condens. Matter
21
,
395502
(
2009
).
36.
Chapter 3—progress in semiconductor β-Ga2O3
,” in
Ultra-Wide Bandgap Semiconductor Materials
, Materials Today, edited by
M.
Liao
,
B.
Shen
, and
Z.
Wang
(
Elsevier
,
2019
), pp.
263
345
.
37.
H.
Peelaers
and
C. G.
Van de Walle
, “
Brillouin zone and band structure of β-Ga2O3
,”
Phys. Status Solidi B
252
,
828
832
(
2015
).
38.
S.
Knight
,
A.
Mock
,
R.
Korlacki
,
V.
Darakchieva
,
B.
Monemar
,
Y.
Kumagai
,
K.
Goto
,
M.
Higashiwaki
, and
M.
Schubert
, “
Electron effective mass in Sn-doped monoclinic single crystal β-Ga2O3 oxide determined by mid-infrared optical Hall effect
,”
Appl. Phys. Lett.
112
,
012103
(
2018
).
39.
H.
He
,
R.
Orlando
,
M. A.
Blanco
,
R.
Pandey
,
E.
Amzallag
,
I.
Baraille
, and
M.
Rérat
, “
First-principles study of the structural, electronic, and optical properties of β-Ga2O3 in its monoclinic and hexagonal phases
,”
Phys. Rev. B
74
,
195123
(
2006
).
40.
X.
Ma
,
Y.
Zhang
,
L.
Dong
, and
R.
Jia
, “
First-principles calculations of electronic and optical properties of aluminum-doped β-Ga2O3 with intrinsic defects
,”
Results Phys.
7
,
1582
1589
(
2017
).
41.
H.
Fröhlich
, “
Electrons in lattice fields
,”
Adv. Phys.
3
,
325
361
(
1954
).
42.
M.
Lundstrom
,
Fundamentals of Carrier Transport
, 2nd ed. (
Cambridge University Press
,
2000
).
43.
D. L.
Rode
, “
Theory of electron galvanomagnetics in crystals—Hall effect in semiconductors and semimetals
,”
Phys. Status Solidi B
55
,
687
696
(
1973
).
44.
R.
Cuscó
,
N.
Doménech-Amador
,
P.
Hung
,
W.-Y.
Loh
,
R.
Droopad
, and
L.
Artús
, “
Raman scattering study of LO phonon-plasmon coupled modes in p-type ingaas
,”
J. Alloys Compd.
634
,
87
93
(
2015
).
45.
T.
Kozawa
,
T.
Kachi
,
H.
Kano
,
Y.
Taga
,
M.
Hashimoto
,
N.
Koide
, and
K.
Manabe
, “
Raman scattering from LO phonon-plasmon coupled modes in gallium nitride
,”
J. Appl. Phys.
75
,
1098
1101
(
1994
).
46.
A.
Mlayah
,
R.
Carles
,
E.
Bedel
, and
A.
Muñoz-Yagüe
, “
Polar phonon-intersubband plasmon coupling in Si delta-doped GaAs
,”
J. Appl. Phys.
74
,
1072
1078
(
1993
).
47.
L.
Artús
,
R.
Cuscó
,
J.
Ibáñez
,
N.
Blanco
, and
G.
González-Díaz
, “
Raman scattering by LO phonon-plasmon coupled modes in n-type InP
,”
Phys. Rev. B
60
,
5456
5463
(
1999
).
48.
R. J.
Bell
,
T. J.
McMahon
, and
D. G.
Rathbun
, “
Longitudinal optical phonon-plasmon coupling in CdS
,”
J. Appl. Phys.
39
,
48
51
(
1968
).
49.
M. V.
Klein
,
B. N.
Ganguly
, and
P. J.
Colwell
, “
Theoretical and experimental study of raman scattering from coupled LO-phonon-plasmon modes in silicon carbide
,”
Phys. Rev. B
6
,
2380
2388
(
1972
).
50.
J.-L.
Farvacque
and
F.
Carosella
, “
Intrinsic free carrier mobility of quantum wells in polar materials
,”
Phys. Rev. B
72
,
125344
(
2005
).
51.
W.
Xiaoguang
,
F. M.
Peeters
, and
J. T.
Devreese
, “
Plasmon-phonon coupling in a two-dimensional electron gas
,”
Phys. Rev. B
32
,
6982
6985
(
1985
).
52.
F. M.
Peeters
,
X.
Wu
, and
J. T.
Devreese
, “
Coupled plasmon–LO-phonon modes in GaxIn1−xAs heterostructures
,”
Phys. Rev. B
36
,
7518
7522
(
1987
).
53.
M.
Schubert
,
A.
Mock
,
R.
Korlacki
,
S.
Knight
,
Z.
Galazka
,
G.
Wagner
,
V.
Wheeler
,
M.
Tadjer
,
K.
Goto
, and
V.
Darakchieva
, “
Longitudinal phonon plasmon mode coupling in β-Ga2O3
,”
Appl. Phys. Lett.
114
,
102102
(
2019
).
54.
P. Y.
Yu
and
M.
Cardona
,
Fundamentals of Semiconductors Physics and Materials Properties
(
Springer
Berlin Heidelberg
,
2010
).
55.
K.
Ghosh
and
U.
Singisetti
, “
Thermoelectric transport coefficients in mono-layer MoS2 and WSe2: Role of substrate, interface phonons, plasmon, and dynamic screening
,”
J. Appl. Phys.
118
,
135711
(
2015
).
56.
N.
Preissler
,
O.
Bierwagen
,
A. T.
Ramu
, and
J. S.
Speck
, “
Electrical transport, electrothermal transport, and effective electron mass in single-crystalline In2O3 films
,”
Phys. Rev. B
88
,
085305
(
2013
).
57.
A. T.
Ramu
,
L. E.
Cassels
,
N. H.
Hackman
,
H.
Lu
,
J. M. O.
Zide
, and
J. E.
Bowers
, “
Rigorous calculation of the Seebeck coefficient and mobility of thermoelectric materials
,”
J. Appl. Phys.
107
,
083707
(
2010
).
58.
W.
Liu
and
A. A.
Balandin
, “
Thermoelectric effects in wurtzite GaN and AlxGa1xN alloys
,”
J. Appl. Phys.
97
,
123705
(
2005
).
59.
S.
Tanaka
,
M.
Takiishi
,
K.
Miyazaki
, and
H.
Tsukamoto
, “
Measurements of thermal conductivity of thin films by 3ω method
,” in
International Conference on Micro/Nanoscale Heat Transfer
(
ASME
2008
).
60.
A.
Balandin
and
K. L.
Wang
, “
Effect of phonon confinement on the thermoelectric figure of merit of quantum wells
,”
J. Appl. Phys.
84
,
6149
6153
(
1998
).
61.
Z.
Chen
,
X.
Zhang
, and
Y.
Pei
, “
Manipulation of phonon transport in thermoelectrics
,”
Adv. Mater.
30
,
1705617
(
2018
).
62.
R.
Venkatasubramanian
,
E.
Siivola
,
T.
Colpitts
, and
B.
O'Quinn
, “
Thin-film thermoelectric devices with high room-temperature figures of merit
,”
Nature
413
,
597
602
(
2001
).

Supplementary Material

You do not currently have access to this content.