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We work microscope equipments produced by
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CaF2 |
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CdF2 |
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MnF2 |
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Si |
| O.V.
Anisimov, A.G. Banshchikov, A.V. Krupin, M.M. Moisseeva,
N.S. Sokolov,
V.P. Ulin, N.L. Yakovlev “Manganese Fluoride Epitaxial Growth on Si(111)” Thin Solid Films, v.367/1-2, pp.199-202, 2000 Epitaxial MnF2 layers were grown on CaF2/Si(111)
substrates using molecular beam epitaxy. Layer-by-layer growth was observed
at room temperature. The first 3 molecular layers of MnF2
have cubic fluorite lattice inherited from CaF2. Thicker layers have
tetragonal lattice of rutile with (110) plane
parallel to the substarte surface and [001] axis along <-110> directions
of CaF2. Thus there are 3 orientations of
rotational domains in the MnF2 layer. At a temperature higher than400C,
nucleation begins with three-dimensional clusters which are aligned with
respect to steps on CaF2 surface. After coalescence
of the clusters, single domain film can be obtained.
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N.S.Sokolov, S.M.Suturin“MBE growth peculiarities of fluoride (CdF2-CaF2) thin film structures”, Thin Solid Films, v.367/1-2, pp.112-119, 2000Calcium and cadmium fluorides have the same fluorite-type crystal structure with relatively close to each other lattice parameters (da/a~1.4%). The specific features of the MBE growth of the CdF2 and CaF2 layers as well as of CdF2-CaF2 heterostructures, have been analysed in this work, using both previously published and recently obtained data. The surface morphology of the CdF2 layers, studied by AFM, was found to depend strongly on the growth temperature. The surface of the high temperature layers (400C and higher) consisted of wide atomically flat terraces corresponding to the 2D growth mode. In contrast to that, well pronounced pyramidal mounds indicating the 3D growth mode were observed on the layers grown at below 300C. Similar 3D growth was found for 10-30 monolayers thick CaF2 films grown at 500-650C. The CdF2-CaF2 superlattices with the period ranging from 2 to 40 nm were also studied. Though all the SLs were single crystalline, their surface morphology varied with the period. While the short-period SLs had a smooth surface, the long-period SLs revealed multilayer columns likely due to rotational twins. The RHEED investigations of the short-period SLs showed an asymmetry of the "CaF2 on CdF2" and "CdF2 on CaF2" interfaces. The possible mechanisms relevant to this phenomenon have been discussed. |
Web master: MarinaMoisseeva
E-mail: marina@fl.ioffe.rssi.ru;
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