High-resolution Rutherford backscattering study of ultrathin YBaCuO film growth on SrTiO3 and MgO

Medium energy ion scattering in combination with an electrostatic high-resolution detector system was applied to study the initial growth of YBaCuO thin films on (100) SrTiO3 and MgO substrates. Ultrathin films with thicknesses in the range of 0.4 to 3.6 nm were deposited by inverted cylindrical magnetron sputtering. From the absolute determination of coverage as a function of depth the following growth features were deduced: on both substrates the films grow in blocks of one unit cell and full coverage with a homogeneous film is achieved at 3.6-nm thickness. In the initial stage of nucleation, on SrTiO3 the growth of an additional block layer is initiated only after completion of the preceding layer, while island growth is observed on MgO with different coverage values on three layer levels appearing simultaneously.