Understanding the properties of N-implanted β-Ga2O3 is fundamental for the optimization of doping and isolation structures based on gallium oxide. This paper reports an extensive analysis of the impact of thermal annealing on the concentration and properties of deep levels in N-implanted β-Ga2O3 Schottky barrier diodes by means of capacitance isothermal transient spectroscopy. Samples with annealing temperatures from 800 to 1200 °C were considered. The original results presented in this paper demonstrate the following: (a) The instability of current–voltage characteristics detected for all the samples under test can be attributed to the presence of three electron traps with activation energies of 0.6, 0.7, and 1 eV, consistent with previous reports in β-Ga2O3. (b) The detected traps are not the nitrogen level but intrinsic defects whose concentration is increased by the implantation process. (c) The concentration of deep levels decreases as the annealing temperature increases, demonstrating that the annealing process can effectively restore the quality of the material while keeping the conductivity decrease related to the presence of the nitrogen. Finally, (d) we demonstrate that the residual leakage and the turn-on voltage shift are correlated with the Arrhenius signature of the detected deep levels. An interpretation is proposed to explain the measurement results.
REFERENCES
1.
M.
Higashiwaki
and G. H.
Jessen
, “Guest editorial: The Dawn of gallium oxide microelectronics
,” Appl. Phys. Lett.
112
, 060401
(2018
). 2.
S. I.
Stepanov
, V. I.
Nikolaev
, V. E.
Bougrov
, and A. E.
Romanov
, “Gallium oxide: Properties and applications—A review
,” Rev. Adv. Mater. Sci.
44
, 63
(2016
); available at https://www.scopus.com/record/display.uri?eid=2-s2.0-84962599644&origin=inward&txGid=25b71662c91b91b4fbec5930c8086bd53.
S. J.
Pearton
, F.
Ren
, M.
Tadjer
, and J.
Kim
, “Perspective: Ga2O3 for ultra-high power rectifiers and MOSFETS
,” J. Appl. Phys.
124
, 220901
(2018
). 4.
M.
Higashiwaki
, R.
Kaplar
, J.
Pernot
, and H.
Zhao
, “Ultrawide bandgap semiconductors
,” Appl. Phys. Lett.
118
, 200401
(2021
). 5.
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
). 6.
B. J.
Baliga
, “Semiconductors for high-voltage, vertical channel field-effect transistors
,” J. Appl. Phys.
53
, 1759
(1982
). 7.
M. H.
Wong
and M.
Higashiwaki
, “Gallium oxide field effect transistors—Establishing new frontiers of power switching and radiation-hard electronics
,” Int. J. High Speed Electron. Syst.
28
, 1940002
(2019
). 8.
K.
Tetzner
, E.
Bahat Treidel
, O.
Hilt
, A.
Popp
, S.
Bin Anooz
, G.
Wagner
, A.
Thies
, K.
Ickert
, H.
Gargouri
, and J.
Wurfl
, “Lateral 1.8 kV β-Ga2O3 MOSFET with 155 MW/cm2 power figure of merit
,” IEEE Electron Device Lett.
40
, 1503
(2019
). 9.
M. H.
Wong
, K.
Sasaki
, A.
Kuramata
, S.
Yamakoshi
, and M.
Higashiwaki
, “Field-plated Ga2O3 MOSFETs with a breakdown voltage of over 750V
,” IEEE Electron Device Lett.
37
, 212
(2016
). 10.
Z.
Hu
, K.
Nomoto
, W.
Li
, R.
Jinno
, T.
Nakamura
, D.
Jena
, and H.
Xing
, 1.6 kV vertical Ga2O3 FinFETs with source-connected field plates and normally-off operation
, in 2019 31st International Symposium on Power Semiconductor Devices and ICs
(IEEE
, 2019
), pp. 483
–486
. 11.
M. H.
Wong
, K.
Goto
, H.
Murakami
, Y.
Kumagai
, and M.
Higashiwaki
, “Current aperture vertical β-Ga2O3 MOSFETs fabricated by N- and Si-ion implantation doping
,” IEEE Electron Device Lett.
40
, 431
(2019
). 12.
Z.
Hu
, K.
Nomoto
, W.
Li
, N.
Tanen
, K.
Sasaki
, A.
Kuramata
, T.
Nakamura
, D.
Jena
, and H. G.
Xing
, “Enhancement-Mode Ga2O3 vertical transistors with breakdown voltage >1 kV
,” IEEE Electron Device Lett.
39
, 869
(2018
). 13.
J. B.
Varley
, J. R.
Weber
, A.
Janotti
, and C. G.
Van de Walle
, “Oxygen vacancies and donor impurities in β-Ga2O3
,” Appl. Phys. Lett.
97
, 142106
(2010
). 14.
M.
Higashiwaki
, Gallium Oxide—Material Proprieties, Crystal Growth and Devices
(Springer, 2020
).15.
K.
Tetzner
, A.
Thies
, E. B.
Treidel
, F.
Brunner
, G.
Wagner
, and J.
Würfl
, “Selective area isolation of β-Ga2O3 using multiple energy nitrogen ion implantation
,” Appl. Phys. Lett.
113
, 172104
(2018
). 16.
X.
Xia
, M.
Xian
, C.
Fares
, R.
Sharma
, M. E.
Law
, F.
Ren
, and S. J.
Pearton
, “Nitrogen ion-implanted resistive regions for edge termination of vertical Ga2O3 rectifiers
,” J. Vac. Sci. Technol. A
39
, 063405
(2021
). 17.
M. H.
Wong
, C.-H.
Lin
, A.
Kuramata
, S.
Yamakoshi
, H.
Murakami
, Y.
Kumagai
, and M.
Higashiwaki
, “Acceptor doping of β-Ga2O3 by Mg and N ion implantations
,” Appl. Phys. Lett.
113
, 102103
(2018
). 18.
A. T.
Neal
, S.
Mou
, S.
Rafique
, H.
Zhao
, E.
Ahmadi
, J. S.
Speck
, K. T.
Stevens
, J. D.
Blevins
, D. B.
Thomson
, N.
Moser
, K. D.
Chabak
, and G. H.
Jessen
, “Donors and deep acceptors in β-Ga2O3
,” Appl. Phys. Lett.
113
, 062101
(2018
). 19.
H.
Peelaers
, J. L.
Lyons
, J. B.
Varley
, and C. G.
Van De Walle
, “Deep acceptors and their diffusion in Ga2O3
,” APL Mater.
7
, 022519
(2019
). 20.
R.
Sharma
, M. E.
Law
, F.
Ren
, A. Y.
Polyakov
, and S. J.
Pearton
, “Diffusion of dopants and impurities in β-Ga2O3
,” J. Vac. Sci. Technol. A
39
, 060801
(2021
). 21.
C.
De Santi
, A.
Nardo
, M. H.
Wong
, K.
Goto
, A.
Kuramata
, S.
Yamakoshi
, H.
Murakami
, Y.
Kumagai
, M.
Higashiwaki
, G.
Meneghesso
, E.
Zanoni
, and M.
Meneghini
, “Stability and degradation of isolation and surface in Ga2O3 devices
,” Microelectron. Reliab.
100–101
, 113453
(2019
). 22.
A.
Mishra
, T.
Moule
, M. J.
Uren
, M. H.
Wong
, K.
Goto
, H.
Murakami
, Y.
Kumagai
, M.
Higashiwaki
, and M.
Kuball
, “Characterization of trap states in buried nitrogen-implanted β-Ga2O3
,” Appl. Phys. Lett.
117
, 243505
(2020
). 23.
C.
De Santi
, M.
Fregolent
, M.
Buffolo
, M. H.
Wong
, M.
Higashiwaki
, G.
Meneghesso
, E.
Zanoni
, and M.
Meneghini
, “Carrier capture kinetics, deep levels, and isolation properties of β-Ga2O3 Schottky-barrier diodes damaged by nitrogen implantation
,” Appl. Phys. Lett.
117
, 262108
(2020
). 24.
J.
Zhang
, J.
Shi
, D. C.
Qi
, L.
Chen
, and K. H. L.
Zhang
, “Recent progress on the electronic structure, defect, and doping properties of Ga2O3
,” APL Mater.
8
, 020906
(2020
).25.
D. V.
Lang
, “Deep-level transient spectroscopy: A new method to characterize traps in semiconductors
,” J. Appl. Phys.
45
, 3023
(1974
). 26.
H.
Okushi
and Y.
Tokumaru
, “Isothermal capacitance transient spectroscopy
,” Jpn. J. Appl. Phys.
20
, 261
(1981
). 27.
P.
Blood
and J. W.
Orton
, The Electrical Characterization of Semiconductors Majority Carriers and Electron States
(Academic Press
, London
, 1992
).28.
Z.
Wang
, X.
Chen
, F.-F.
Ren
, S.
Gu
, and J.
Ye
, “Deep-level defects in gallium oxide
,” J. Phys. D: Appl. Phys.
54
, 043002
(2021
). 29.
K.
Irmscher
, Z.
Galazka
, M.
Pietsch
, R.
Uecker
, and R.
Fornari
, “Electrical properties of β-Ga2O3 single crystals grown by the Czochralski method
,” J. Appl. Phys.
110
, 063720
(2011
). 30.
M.
Fregolent
, M.
Buffolo
, C.
De Santi
, S.
Hasegawa
, J.
Matsumura
, H.
Nishinaka
, M.
Yoshimoto
, G.
Meneghesso
, E.
Zanoni
, and M.
Meneghini
, “Deep levels and carrier capture kinetics in n-GaAsBi alloys investigated by deep level transient spectroscopy
,” J. Phys. D: Appl. Phys.
54
, 345109
(2021
). 31.
Z.
Zhang
, E.
Farzana
, A. R.
Arehart
, and S. A.
Ringel
, “Deep level defects throughout the bandgap of (010) β-Ga2O3 detected by optically and thermally stimulated defect spectroscopy
,” Appl. Phys. Lett.
108
, 052105
(2016
). 32.
J. F.
Mcglone
, Z.
Xia
, Y.
Zhang
, C.
Joishi
, S.
Lodha
, S.
Rajan
, S. A.
Ringel
, and A. R.
Arehart
, “Trapping effects in Si-doped-Ga2O3 MESFETs on an Fe-doped-Ga2O3 substrate
,” IEEE Electron Device Lett.
39
, 1042
(2018
). 33.
M. E.
Ingebrigtsen
, J. B.
Varley
, A. Y.
Kuznetsov
, B. G.
Svensson
, G.
Alfieri
, A.
Mihaila
, U.
Badstübner
, and L.
Vines
, “Iron and intrinsic deep level states in Ga2O3
,” Appl. Phys. Lett.
112
, 042104
(2018
). 34.
H.
Ghadi
, J. F.
McGlone
, C. M.
Jackson
, E.
Farzana
, Z.
Feng
, A. F. M. A. U.
Bhuiyan
, H.
Zhao
, A. R.
Arehart
, and S. A.
Ringel
, “Full bandgap defect state characterization of β-Ga2O3 grown by metal organic chemical vapor deposition
,” APL Mater.
8
, 021111
(2020
). 35.
E.
Farzana
, E.
Ahmadi
, J. S.
Speck
, A. R.
Arehart
, and S. A.
Ringel
, “Deep level defects in Ge-doped (010) β-Ga2O3 layers grown by plasma-assisted molecular beam epitaxy
,” J. Appl. Phys.
123
, 161410
(2018
). 36.
A. Y.
Polyakov
, N. B.
Smirnov
, I. V.
Shchemerov
, E. B.
Yakimov
, J.
Yang
, F.
Ren
, G.
Yang
, J.
Kim
, A.
Kuramata
, and S. J.
Pearton
, “Point defect induced degradation of electrical properties of Ga2O3 by 10 MeV proton damage
,” Appl. Phys. Lett.
112
, 032107
(2018
). 37.
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.
55
, 1202A2
(2016
). 38.
S.
Bhandari
and M. E.
Zvanut
, “Charge trapping at Fe due to midgap levels in Ga2O3
,” J. Appl. Phys.
129
, 085703
(2021
). 39.
M.
Meneghini
, I.
Rossetto
, D.
Bisi
, A.
Stocco
, A.
Chini
, A.
Pantellini
, C.
Lanzieri
, A.
Nanni
, G.
Meneghesso
, and E.
Zanoni
, “Buffer traps in Fe-doped AlGaN/GaN HEMTs: Investigation of the physical properties based on pulsed and transient measurements
,” IEEE Trans. Electron Devices
61
, 4070
(2014
). 40.
M. E.
Ingebrigtsen
, A. Y.
Kuznetsov
, B. G.
Svensson
, G.
Alfieri
, A.
Mihaila
, U.
Badstübner
, A.
Perron
, L.
Vines
, and J. B.
Varley
, “Impact of proton irradiation on conductivity and deep level defects in β-Ga2O3
,” APL Mater.
7
, 022510
(2019
). © 2021 Author(s). Published under an exclusive license by AIP Publishing.
2021
Author(s)
You do not currently have access to this content.
