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In situ and real‐time monitoring of structure formation during non‐reactive sputter deposition of lanthanum and reactive sputter deposition of lanthanum nitride
Author(s) -
Krause Bärbel,
Kuznetsov Dmitry S.,
Yakshin Andrey E.,
Ibrahimkutty Shyjumon,
Baumbach Tilo,
Bijkerk Fred
Publication year - 2018
Publication title -
journal of applied crystallography
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.429
H-Index - 162
ISSN - 1600-5767
DOI - 10.1107/s1600576718007367
Subject(s) - materials science , wurtzite crystal structure , nitride , lanthanum , amorphous solid , sputtering , crystallite , sputter deposition , thin film , crystallography , mineralogy , analytical chemistry (journal) , nanotechnology , inorganic chemistry , metallurgy , chemistry , zinc , layer (electronics) , chromatography
Lanthanum and lanthanum nitride thin films were deposited by magnetron sputtering onto silicon wafers covered by natural oxide. In situ and real‐time synchrotron radiation experiments during deposition reveal that lanthanum crystallizes in the face‐centred cubic bulk phase. Lanthanum nitride, however, does not form the expected NaCl structure but crystallizes in the theoretically predicted metastable wurtzite and zincblende phases, whereas post‐growth nitridation results in zincblende LaN. During deposition of the initial 2–3 nm, amorphous or disordered films with very small crystallites form, while the surface becomes smoother. At larger thicknesses, the La and LaN crystallites are preferentially oriented with the close‐packed lattice planes parallel to the substrate surface. For LaN, the onset of texture formation coincides with a sudden increase in roughness. For La, the smoothing process continues even during crystal formation, up to a thickness of about 6 nm. This different growth behaviour is probably related to the lower mobility of the nitride compared with the metal. It is likely that the characteristic void structure of nitride thin films, and the similarity between the crystal structures of wurtzite LaN and La 2 O 3 , evoke the different degradation behaviours of La/B and LaN/B multilayer mirrors for off‐normal incidence at 6. x nm wavelength.