MBE-LEEM: A UK facility for the ultimate control of complex epitaxy

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This first grant project will develop an MBE-LEEM system, combining in-situ state-of-the-art Molecular Beam Epitaxy and a Low Energy Electron Microscope. The project will increase capabilities in sample exchange between institutions, enabling the analysis of nucleation on complex samples, increase reproducibility and accuracy of flux measurements, increase reproducibility and accuracy of temperature control, increase the number of material sources, enabling the growth of new materials, increase safety, reduce down-time of the system and increase control during surface preparation. The development of the MBE-LEEM will enable close collaboration between Cardiff University and EPSRC National Centre for III-V Technologies and with IQE, a world leading semiconductor wafer company. The system will be used for basic research, providing a wealth of data on nucleation dynamics and key epitaxial processes for theorists across UK, and providing industrial and academic partners with a unique characterization technique to determine optimum growth parameters in complex epitaxial processes by analysing growth dynamics. The extended capabilities of the MBE-LEEM will be tested by studying the nucleation of MnAs on InAs, determining the conditions for nucleation of Zinc-Blende MnAs. The nucleation of half-metallic MnAs on an InAs buffer layer with thickness below 2 monolayers was shown by Kim et al. in 2006, but the process has not been reproduced and no explanation on the mechanism leading to Zinc-Blende MnAs has been provided. MBE-LEEM will produce videos of the nucleation of MnAs on InAs with different thicknesses, highlighting the evolution of MnAs crystal structure and morphology during nucleation. The fabrication of half-metallic semiconductors can be key for the development of spintronics. Follow-up research is projected after this first grant development project in order to analyse magnetic properties of half-metallic MnAs, and to apply MBE-LEEM to other key research on epitaxial processes, such as the integration of GaAs on Silicon, or the nucleation of nanostructures.