Research Of Thickness And Preferred Orientation Behaviors Of Bi2201 Films By X-ray

In this dissertation, Bi2201 films on MgO (001) single crystal were prepared by MBE method. The experimental technique was studied. In addition, the preferred orientation behaviors of the films were investigated in detail. The main content of the dissertation are as follows:1. Study on the thicknesses and growth mode of Bi-2201 films prepared by MBE. The evaporation rate of Bi and Cu as function of vapor temperature were studied. The Function of was devised and settled. So the higher reliability and control precision of the evaporation rate of Bi and Cu was available. Above all, high purity of Bi2201 films was obtained. Study of Bi2201 epitaxial thin films by XRR. Results reveal that the growth mode of Bi2201 thin films was S-K growth mode, and the Bi2201 critical thickness of 2D layer growth to 3D island growth was 17.347nm (about 7 unit cells).2. Research of the preferred orientation behaviors of Bi2201 films on MgO (001) single crystals. Results reveal that Bi2201 thin films were heteroepitaxially grown on MgO (001), with rotation 45°and (001)[100]Bi2201//(001)[110]MgO. The mismatchδbetween the two crystals was 9.4%.3. The property of Bi2201 films in-plane orientation varying with thickness. Before the thickness of 17.347nm, the film grown with 2D layer growth mode and only 4 diffraction peaks of Bi2201 in XRDΦscan. After that, the film grown around original orientation in plane and the XRDΦscan diffraction peaks were caused broaden, with the film growth mode changing to 3D island mode from 2D layers'. With the film growing along, two symmetrical new orientation in plane separated from the original was observed, while the fixed angle between one new orientation and the original was±33.7°. This angle did not vary with different thickness samples. As the film growing along, another new orientation separated with±17°fixed angle. The process would not cease from separating to exhibit the intrinsic in-plane orientation.