Implantation, damage, and regrowth of high Tc superconductors
Abstract We have observed superconductivity in thin films of (La1−xSrx)2CuOy which are fabricated by implanting evaporated La/Cu multilayer films with Sr and annealing in oxygen. The films are insulating and partially transparent as-implanted, but they darken and become conducting at annealing temperatures as low as 500°C. The resistive behavior is very sensitive to the annealing conditions and the superconducting layer appears to be buried beneath the surface. Similarly, implantation of F, O, and Ne into single crystals and high quality (χmin
Investigation of films of YBa2Cu3O7 using Rutherford backscattering spectrometry
Abstract Rutherford backscattering spectrometry (RBS) has been applied to films of the high-temperature superconductor YBa2Cu3O7. The films were prepared by rf and dc sputtering and silk-screen printing onto substrates of alumina, sapphire and magnesia. Some of the samples were exposed to various heat treatments in order to promote the superconducting phase. A 2 MeV beam of He+ particles from the 3 MV Dynamitron accelerator at Birmingham University's School of Physics and Space Research was employed for the RBS measurements. The composition and the depth profile of the elements in the films were determined by simulating the observed RBS spectra with a simulation software package. The simulations show that the heat treatment causes marked interdiffusion of the film and substrate. The experimental results and the computer simulations shown in this paper illustrate the advantages of using RBS to characterise films of the new superconducting materials.
High-resolution x-ray diffraction studies of InGaAs(P)/InP superlattices grown by gas-source molecular-beam epitaxy
High‐resolution x‐ray diffraction studies have been carried out to determine the structural perfection and periodicity for a number of high‐quality InGaAs/InP superlattices and one InGaAsP/InP superlattice grown by gas‐source molecular‐beam epitaxy. For comparison, high‐resolution diffraction both with a three‐crystal geometry and with a four‐crystal monochromator was used along with conventional double‐crystal x‐ray diffractometry. The best resolution in the x‐ray satellite patterns was obtained with the four‐crystal monochromator, providing a resolution of one molecular layer in the periodicity of the superlattice. The presence of sharp satellite reflections in the x‐ray diffraction profiles demonstrate smooth interfaces with well‐defined modulated structures which could be derived from a kinematical diffraction step model. For some superlattices, excellent agreement between the step model and the measurements is obtained when the model assumes that each period consists only of the well and the barrier ...