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Pulsed laser deposition of KNbO3 thin films

Pulsed laser deposition of KNbO3 thin films
Pulsed laser deposition of KNbO3 thin films
The laser ablation of stationary KNbO3 single crystal targets induces a Nb enrichment of the target surface. In rotated targets this effect is observed only in those areas irradiated with low laser fluence. The composition of the plasma formed close to the target surface is congruent with the target composition; however, at further distances K-deficient films are formed due to the preferential backscattering of K in the plasma. This loss may be compensated for by using K-rich ceramic targets. Best results so far have been obtained with [K]/[Nb] = 2.85 target composition, and crystalline KNbO3 films are formed when heating the substrates to 650 °C. Films formed on (100)MgO single crystals are usually single phase and oriented with the (110) film plane parallel to the (100) substrate surface. (100)NbO may coexist with KNbO3 on (100)MgO. At substrate temperatures higher than 650 °C, niobium diffuses into MgO forming Mg4Nb2O9 and NbO, leading to K evaporation from the film. Films formed on (001) alpha-Al2O3 (sapphire) show the coexistence of (111), (110), and (001) orientations of KNbO3, and the presence of NbO2 is also observed. KNbO3 films deposited on (001)LiNbO3 crystallize with the (111) plane of the film parallel to the substrate surface. For the latter two substrates the Nb diffusion into the substrate is lower than in MgO and consequently the K concentration retained in the film is comparatively larger.
2699-2706
Martin, M.J.
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Alfonso, J.E.
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Mendiola, J.
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Zaldo, C.
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Gill, D.S.
0837886a-5999-478f-8b32-ea1996611c3c
Eason, R.W.
e38684c3-d18c-41b9-a4aa-def67283b020
Chandler, P.J.
df497652-94c6-4987-9fe1-a4b93111dadf
Martin, M.J.
404681a1-831b-4a45-a232-d64690b7df70
Alfonso, J.E.
da7dab92-2998-4776-949c-4e717e8d3235
Mendiola, J.
0c3c5105-7d4c-414c-9857-78bc88310552
Zaldo, C.
fed559d7-64ba-4a7a-91d8-bb2ce13ee8e0
Gill, D.S.
0837886a-5999-478f-8b32-ea1996611c3c
Eason, R.W.
e38684c3-d18c-41b9-a4aa-def67283b020
Chandler, P.J.
df497652-94c6-4987-9fe1-a4b93111dadf

Martin, M.J., Alfonso, J.E., Mendiola, J., Zaldo, C., Gill, D.S., Eason, R.W. and Chandler, P.J. (1997) Pulsed laser deposition of KNbO3 thin films. Journal of Materials Research, 12 (10), 2699-2706. (doi:10.1557/JMR.1997.0359).

Record type: Article

Abstract

The laser ablation of stationary KNbO3 single crystal targets induces a Nb enrichment of the target surface. In rotated targets this effect is observed only in those areas irradiated with low laser fluence. The composition of the plasma formed close to the target surface is congruent with the target composition; however, at further distances K-deficient films are formed due to the preferential backscattering of K in the plasma. This loss may be compensated for by using K-rich ceramic targets. Best results so far have been obtained with [K]/[Nb] = 2.85 target composition, and crystalline KNbO3 films are formed when heating the substrates to 650 °C. Films formed on (100)MgO single crystals are usually single phase and oriented with the (110) film plane parallel to the (100) substrate surface. (100)NbO may coexist with KNbO3 on (100)MgO. At substrate temperatures higher than 650 °C, niobium diffuses into MgO forming Mg4Nb2O9 and NbO, leading to K evaporation from the film. Films formed on (001) alpha-Al2O3 (sapphire) show the coexistence of (111), (110), and (001) orientations of KNbO3, and the presence of NbO2 is also observed. KNbO3 films deposited on (001)LiNbO3 crystallize with the (111) plane of the film parallel to the substrate surface. For the latter two substrates the Nb diffusion into the substrate is lower than in MgO and consequently the K concentration retained in the film is comparatively larger.

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Published date: October 1997

Identifiers

Local EPrints ID: 77920
URI: https://eprints.soton.ac.uk/id/eprint/77920
PURE UUID: c8727c96-582f-46a5-8376-f3b12063387d
ORCID for R.W. Eason: ORCID iD orcid.org/0000-0001-9704-2204

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Date deposited: 11 Mar 2010
Last modified: 19 Jul 2019 01:21

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