D. Huttner et al., HIGH-RESOLUTION RES STUDY OF THE GROWTH AND THE CRYSTALLINE QUALITY OF ULTRATHIN YBACUO FILMS, Nuclear instruments & methods in physics research. Section B, Beam interactions with materials and atoms, 118(1-4), 1996, pp. 578-583
A high energy resolution detection system consisting of a toroidal ele
ctrostatic analyzer combined with a novel two-dimensional detector has
been installed in a UHV scattering chamber, The angular resolution ac
hieved with this system was 0.33 degrees over a range of 23 degrees, a
nd the energy resolution, Delta E/E, was 1.95 X 10(-3) over a range of
2.1% of the pass energy. We applied medium energy ion scattering (200
keV He+ ions) combined with channeling to study the initial growth ph
enomena and the crystalline quality of YBaCuO ultrathin films on (100)
SrTiO3 and MgO substrates exploiting the high depth resolution of the
detection system which was 0.5 nm for YBaCuO, The determination of th
e coverage as a function of depth revealed that on both substrates the
films grow in blocks of one unit cell, But on SrTiO3 the growth of an
additional block layer is initiated only after completion of the prec
eding layer while on MgO island growth is observed with different cove
rage values on three layer levels appearing simultaneously, On SrTiO3
the growth up to a critical thickness of 4 nm is pseudomorphic (chi(mi
n) = 2%); at larger thicknesses strain release accompanied by defect i
ncorporation leads to chi(min) enhancement (12%).