The indirect effect of oxygen background gas on the La/Al ratio during the growth of LaAlO3 (LAO) films by pulsed laser deposition (PLD) is analyzed, in a pressure range between 10−3 and 10−1 mbar. We resort to two complementary investigation methods: Rutherford backscattering spectroscopy and spectrally resolved, time-gated imaging of the laser plume. The first technique allows us to analyze the stoichiometry of the deposited films, and the latter allows us to analyze the plume expansion phase of the PLD process by collecting chemically resolved two-dimensional images of the relevant atomic/molecular species. The comparison between the results obtained by the two techniques allows us to highlight the role of the plume-gas interaction in affecting cations stoichiometry. Our results indicate that, in the considered pressure range, the background oxygen pressure affects the cations stoichiometry of the LAO films, besides determining their oxygen content.
References
1.
A.
Ohtomo
and H. Y.
Hwang
, “A high-mobility electron gas at the LaAlO3/SrTiO3 heterointerface
,” Nature
427
(6973
), 423
–426
(2004
).2.
N.
Reyren
, S.
Thiel
, A. D.
Caviglia
, I.
Fitting Kourkoutis
, G.
Hammerl
, C.
Richter
, C. W.
Schneider
, T.
Kopp
, A.-S.
Rüetschi
, D.
Jaccard
, M.
Gabay
, D. A.
Muller
, J.-M.
Triscone
, and J.
Mannhart
, “Superconducting interfaces between insulating oxides
,” Science
317
(5842
), 1196
–1199
(2007
).3.
A.
Brinkman
, M.
Huijben
, M.
Van Zalk
, J.
Huijben
, U.
Zeitler
, J. C.
Maan
, and H.
Hilgenkamp
, “Magnetic effects at the interface between non-magnetic oxides
,” Nat. Mater.
6
(7
), 493
–496
(2007
).4.
A.
Fête
, C.
Cancellieri
, D.
Li
, D.
Stornaiuolo
, A. D.
Caviglia
, S.
Gariglio
, and J.-M.
Triscone
, “Growth-induced electron mobility enhancement at the LaAlO3/SrTiO3 interface
,” Appl. Phys. Lett.
106
, 051604
(2015
).5.
A.
Sambri
, D.
Christensen
, F.
Trier
, Y.
Chen
, S.
Amoruso
, N.
Pryds
, and X.
Wang
, “Plasma plume effects on the conductivity of amorphous-LaAlO3/SrTiO3 interfaces grown by pulsed laser deposition in O2 and Ar
,” Appl. Phys. Lett.
100
, 231605
(2012
).6.
A.
Kalabukhov
, R.
Gunnarsson
, J.
Börjesson
, E.
Olsson
, D.
Winkler
, and T.
Claeson
, “Effect of various deposition conditions on the electrical properties of LaAlO3/SrTiO3 heterointerfaces
,” J. Phys.: Conf. Ser.
100
(8
), 082039
(2008
).7.
C.
Cancellieri
, N.
Reyren
, S.
Gariglio
, A. D.
Caviglia
, A.
Fête
, and J. M.
Triscone
, “Influence of the growth conditions on the LaAlO3/SrTiO3 interface electronic properties
,” EPL (Europhys. Lett.)
91
(1
), 17004
(2010
).8.
T.
Ohnishi
, M.
Lippmaa
, T.
Yamamoto
, S.
Meguro
, and H.
Koinuma
, “Improved stoichiometry and misfit control in perovskite thin film formation at a critical fluence by pulsed laser deposition
,” Appl. Phys. Lett.
87
, 241919
(2005
).9.
T.
Ohnishi
, K.
Shibuya
, T.
Yamamoto
, and M.
Lippmaa
, “Defects and transport in complex oxide thin films
,” J. Appl. Phys.
103
(10
), 103703
(2008
).10.
D. J.
Keeble
, S.
Wicklein
, R.
Dittmann
, L.
Ravelli
, R. A.
Mackie
, and W.
Egger
, “Identification of a-and b-site cation vacancy defects in perovskite oxide thin films
,” Phys. Rev. Lett.
105
(22
), 226102
(2010
).11.
S.
Wicklein
, A.
Sambri
, S.
Amoruso
, X.
Wang
, R.
Bruzzese
, A.
Koehl
, and R.
Dittmann
, “Pulsed laser ablation of complex oxides: The role of congruent ablation and preferential scattering for the film stoichiometry
,” Appl. Phys. Lett.
101
(13
), 131601
(2012
).12.
G. Z.
Liu
, Q. Y.
Lei
, and X. X.
Xi
, “Stoichiometry of SrTiO3 films grown by pulsed laser deposition
,” Appl. Phys. Lett.
100
(20
), 202902
(2012
).13.
C.
Xu
, S.
Wicklein
, A.
Sambri
, S.
Amoruso
, M.
Moors
, and R.
Dittmann
, “Impact of the interplay between nonstoichiometry and kinetic energy of the plume species on the growth mode of SrTiO3 thin films
,” J. Phys. D: Appl. Phys.
47
(3
), 034009
(2014
).14.
K.
Orsel
, R.
Groenen
, B.
Bastiaens
, G.
Koster
, G.
Rijnders
, and K. J.
Boller
, “Influence of the oxidation state of SrTiO3 plasmas for stoichiometric growth of pulsed laser deposition films identified by laser induced fluorescence
,” APL Mater.
3
(10
), 106103
(2015
).15.
M.
Golalikhani
, Q. Y.
Lei
, G.
Chen
, J. E.
Spanier
, H.
Ghassemi
, C. L.
Johnson
et al, “Stoichiometry of LaAlO3 films grown on SrTiO3 by pulsed laser deposition
,” J. Appl. Phys.
114
(2
), 027008
(2013
).16.
T. C.
Droubay
, L.
Qiao
, T. C.
Kaspar
, M. H.
Engelhard
, V.
Shutthanandan
, and S. A.
Chambers
, “Nonstoichiometric material transfer in the pulsed laser deposition of LaAlO3
,” Appl. Phys. Lett.
97
(12
), 124105
(2010
).17.
E.
Breckenfeld
, R. B.
Wilson
, and L. W.
Martin
, “Effect of growth induced (non) stoichiometry on the thermal conductivity, permittivity, and dielectric loss of LaAlO3 films
,” Appl. Phys. Lett.
103
(8
), 082901
(2013
).18.
H. K.
Sato
, C.
Bell
, Y.
Hikita
, and H. Y.
Hwang
, “Stoichiometry control of the electronic properties of the LaAlO3/SrTiO3 heterointerface
,” Appl. Phys. Lett.
102
(25
), 251602
(2013
).19.
C.
Aruta
, S.
Amoruso
, R.
Bruzzese
, X.
Wang
, D.
Maccariello
, F. M.
Granozio
, and U.
Scotti di Uccio
, “Pulsed laser deposition of SrTiO3/LaGaO3 and SrTiO3/LaAlO3: Plasma plume effects
,” Appl. Phys. Lett.
97
(25
), 252105
(2010
).20.
C.
Aruta
, S.
Amoruso
, G.
Ausanio
, R.
Bruzzese
, E.
Di Gennaro
, M.
Lanzano
et al, “Critical influence of target-to-substrate distance on conductive properties of LaGaO3/SrTiO3 interfaces deposited at 10−1 mbar oxygen pressure
,” Appl. Phys. Lett.
101
(3
), 031602
(2012
).21.
N.
Arnold
, J.
Gruber
, and J.
Heitz
, “Spherical expansion of the vapor plume into ambient gas: an analytical model
,” Appl. Phys. A
69
(1
), S87
–S93
(1999
).22.
S.
Amoruso
, A.
Sambri
, and X.
Wang
, “Propagation dynamics of a LaMnO3 laser ablation plume in an oxygen atmosphere
,” J. Appl. Phys.
100
(1
), 013302
(2006
).23.
A.
Sambri
, C.
Aruta
, E.
Di Gennaro
, X.
Wang
, U.
Scotti di Uccio
, F.
Miletto Granozio
, and S.
Amoruso
, “Effects of oxygen background pressure on the stoichiometry of a LaGaO3 laser ablation plume investigated by time and spectrally resolved two-dimensional imaging
,” J. App. Phys.
119
, 125301
(2016
).24.
M. P.
Warusawithana
, C.
Richter
, J. A.
Mundy
, P.
Roy
, J.
Ludwig
, S.
Paetel
et al, “LaAlO3 stoichiometry is key to electron liquid formation at LaAlO3/SrTiO3 interfaces
,” Nat. Commun.
4
, 2351
(2013
).25.
D. B.
Geohegan
and A. A.
Puretzky
, “Laser Ablation plume thermalization dynamics in background gases: combined imaging, optical absorption and emission spectroscopy, and ion probe measurements
,” Appl. Surf. Sci.
96–98
, 131
–138
(1996
).26.
R. W. B.
Pearse
, A. G.
Gaydon
, R. W. B.
Pearse
, and A. G.
Gaydon
, The Identification of Molecular Spectra
(Chapman and Hall
, London
, 1976
), Vol. 297, p. 293
.27.
M.
Mayer
, AIP Conf. Proc.
475
, 541
–544
(1999
).28.
J.
Chen
, M.
Döbeli
, D.
Stender
, K.
Conder
, A.
Wokaun
, C. W.
Schneider
, and T.
Lippert
, “Plasma interactions determine the composition in pulsed laser deposited thin films
,” Appl. Phys. Lett.
105
(11
), 114104
(2014
).29.
A.
Ojeda-GP
, C. W.
Schneider
, M.
Döbeli
, T.
Lippert
, and A.
Wokaun
, “Angular distribution of species in pulsed laser deposition of LaxCa1−xMnO3
,” Appl. Surf. Sci.
336
, 150
–156
(2015
).30.
A.
Ojeda-GP
, C. W.
Schneider
, M.
Döbeli
, T.
Lippert
, and A.
Wokaun
, “The importance of pressure and mass ratios when depositing multi-element oxide thin films by pulsed laser deposition
,” Appl. Surf. Sci.
389
, 126
–134
(2016
).31.
A.
Sambri
, S.
Amoruso
, X.
Wang
, M.
Radovic
, F. M.
Granozio
, and R.
Bruzzese
, “Substrate heating influence on plume propagation during pulsed laser deposition of complex oxides
,” Appl. Phys. Lett.
91
(15
), 151501
(2007
).32.
S.
Amoruso
, C.
Aruta
, R.
Bruzzese
, X.
Wang
, and U.
Scotti di Uccio
, “Substrate heating influence on the deposition rate of oxides during pulsed laser deposition in ambient gas
,” Appl. Phys. Lett.
98
(10
), 101501
(2011
).33.
S.
Amoruso
, J.
Schou
, and J. G.
Lunney
, “Multiple-scattering effects in laser ablation plume propagation in gases
,” Europhys. Lett.
76
(3
), 436
–442
(2006
).© 2016 Author(s).
2016
Author(s)
You do not currently have access to this content.
