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@ARTICLE{Aslam:154093,
author = {Aslam, N. and Longo, V. and Keuning, W. and Roozeboom, F.
and Kessels, W. M. M. and Waser, R. and Hoffmann-Eifert, S.},
title = {{I}nfluence of stoichiometry on the performance of {MIM}
capacitors from plasma-assisted {ALD} {S}r x {T}i y {O} z
films},
journal = {Physica status solidi / A},
volume = {211},
number = {2},
issn = {1862-6300},
address = {Weinheim},
publisher = {Wiley-VCH},
reportid = {FZJ-2014-03495},
pages = {389 - 396},
year = {2014},
abstract = {Strontium titanate, SrxTiyOz (STO), thin films with various
cation stoichiometries were deposited by plasma-assisted
atomic layer deposition (ALD) using cyclopentadienyl-based
metal precursors and oxygen plasma as counter-reactant.
[Sr]/([Sr] + [Ti]) compositions ranging from 0.46 to
0.57 were obtained by changing the (SrO)/(TiO2) ALD cycle
ratios. As-deposited 15–30 nm thick SrxTiyOz films
prepared at 350 °C on Pt-coated silicon substrates were
amorphous. Post-annealing at 600/650 °C for 10 min
under N2 gas resulted in a crystallization into the
perovskite phase. Stoichiometric STO and Sr-rich STO films
exhibited a certain degree of (111) texture while the
Ti-rich STO films showed a lower degree of crystallization.
Crystallized layers exhibited a smaller band gap Eg than
amorphous ones, while within the stoichiometry series the
value of Eg increased with increasing Sr-content. Within the
stoichiometry series Pt/STO/Pt structures with Sr-rich STO
films showed the lowest leakage current densities. At
1.0 V values of about 2 × 10−8 and
5 × 10−6 A cm−2 were obtained for the
as-deposited and the annealed films, respectively. Highest
capacitance density was obtained for 15 nm polycrystalline
stoichiometric SrTiO3 films resulting in a capacitor
equivalent thickness CET of about 0.7 nm. Pt/SrxTiyOz/Pt
capacitors with the STO being in amorphous state exhibited a
positive voltage nonlinearity factor α of about
400 ppm V−2, while the negative α-values for
crystallized films showed a systematic variation with the
stoichiometry, the degree of crystallization and the
thickness of the STO layer. This demonstrates that a broad
performance range of MIM capacitors is accessible by
controlling the stoichiometry and the degree of
crystallization of plasma-assisted ALD SrxTiyOz thin films.},
cin = {PGI-7},
ddc = {530},
cid = {I:(DE-Juel1)PGI-7-20110106},
pnm = {424 - Exploratory materials and phenomena (POF2-424)},
pid = {G:(DE-HGF)POF2-424},
typ = {PUB:(DE-HGF)16},
UT = {WOS:000332000500020},
doi = {10.1002/pssa.201330101},
url = {https://juser.fz-juelich.de/record/154093},
}