TY - JOUR
T1 - Microstructure investigations of the epitaxial growth of ultrathin Bi2Sr2CaCu2Ox superconducting films on (001) SrTiO3 substrates
AU - Amrein, T.
AU - Kabius, B.
AU - Burger, J.
AU - Saemann-Ischenko, G.
AU - Schultz, L.
AU - Urban, K.
N1 - Funding Information:
We would like to thank P. Bauer for his assistance in AFM measurements and P. Schmitt for stimulating discussions. The AFM investigations were supported by the Bayerische Forschungsstiftung Hochtempera-tursupraleitung (FORSUPRA).
PY - 1993/5/10
Y1 - 1993/5/10
N2 - The microstructure of epitaxial, c-axis oriented Bi2Sr2CaCu2Ox superconducting thin films with a mean thickness of 3 to 100 nm on (001) SrTiO3 substrates was studied by plan-view and cross-section transmission electron microscopy (TEM) and atomic force microscopy (AFM). An inductively measured transition temperature could be observed down to 12.5-nm thick films. In plan-view TEM samples, islands were observed, which began to coalesce at a thickness of ≈ 12 nm forming 90° twin domains. By analysis of the Moiré patterns we noted an increasing relaxation of the in-plane lattice parameters of the Bi2Sr2CaCu2Ox phase with increasing film thickness. No Bi2Sr2CaCu2Ox phase was seen in cross-section TEM samples up to a film thickness of 12.5 nm inclusive but two unidentified phases with a fringe spacing in [001] direction of the SrTiO3 of ≈3.3 A ̊ and ≈8 A ̊, respectively. The first one occurred often in discrete film thicknesses of 4, 8 and 12 nm, the other one did not. We suggest, that a precursor mechanism for the growth of the ultrathin Bi2Sr2CaCu2Ox films exists. AFM investigations showed a three stage growth mechanism: 1. appearance of small circular nuclei with a tendency to coalesce, 2. islands form a facet-like film surface and 3. smooth surface. An high density of small holes clustering round needlelike outgrowths was seen in 12.5-nm and thicker films.
AB - The microstructure of epitaxial, c-axis oriented Bi2Sr2CaCu2Ox superconducting thin films with a mean thickness of 3 to 100 nm on (001) SrTiO3 substrates was studied by plan-view and cross-section transmission electron microscopy (TEM) and atomic force microscopy (AFM). An inductively measured transition temperature could be observed down to 12.5-nm thick films. In plan-view TEM samples, islands were observed, which began to coalesce at a thickness of ≈ 12 nm forming 90° twin domains. By analysis of the Moiré patterns we noted an increasing relaxation of the in-plane lattice parameters of the Bi2Sr2CaCu2Ox phase with increasing film thickness. No Bi2Sr2CaCu2Ox phase was seen in cross-section TEM samples up to a film thickness of 12.5 nm inclusive but two unidentified phases with a fringe spacing in [001] direction of the SrTiO3 of ≈3.3 A ̊ and ≈8 A ̊, respectively. The first one occurred often in discrete film thicknesses of 4, 8 and 12 nm, the other one did not. We suggest, that a precursor mechanism for the growth of the ultrathin Bi2Sr2CaCu2Ox films exists. AFM investigations showed a three stage growth mechanism: 1. appearance of small circular nuclei with a tendency to coalesce, 2. islands form a facet-like film surface and 3. smooth surface. An high density of small holes clustering round needlelike outgrowths was seen in 12.5-nm and thicker films.
UR - http://www.scopus.com/inward/record.url?scp=0027594631&partnerID=8YFLogxK
UR - http://www.scopus.com/inward/citedby.url?scp=0027594631&partnerID=8YFLogxK
U2 - 10.1016/0925-8388(93)90703-P
DO - 10.1016/0925-8388(93)90703-P
M3 - Article
AN - SCOPUS:0027594631
SN - 0925-8388
VL - 195
SP - 129
EP - 132
JO - Journal of Alloys and Compounds
JF - Journal of Alloys and Compounds
IS - C
ER -