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

第一个拨款项目将开发MBE-LEEM系统，结合现场最先进的分子束外延和低能电子显微镜。该项目将提高机构之间样品交换的能力，使复杂样品的成核分析成为可能，提高通量测量的可重复性和准确性，提高温度控制的可重复性和准确性，增加材料来源的数量，使新材料的生长成为可能，提高安全性，减少系统停机时间，并增加表面制备过程中的控制。MBE-LEEM的开发将使卡迪夫大学与EPSRC国家III-V技术中心以及世界领先的半导体晶圆公司IQE之间进行密切合作。该系统将用于基础研究，为英国各地的理论家提供丰富的成核动力学和关键外延过程数据，并为工业和学术合作伙伴提供独特的表征技术，通过分析生长动力学来确定复杂外延过程中的最佳生长参数。MBE-LEEM的扩展能力将通过研究InAs上的MnAs成核来测试，确定锌-闪锌矿MnAs成核的条件。Kim等人在2006年证明了半金属MnAs在厚度低于2层的InAs缓冲层上的成核，但这一过程没有被重现，也没有解释导致锌-闪锌矿MnAs的机制。MBE-LEEM将在不同厚度的InAs上制作MnAs成核的视频，突出显示成核过程中MnAs晶体结构和形态的演变。半金属半导体的制造是自旋电子学发展的关键。后续研究计划在第一个资助开发项目之后进行，以分析半金属MnAs的磁性，并将MBE-LEEM应用于其他外延工艺的关键研究，如硅上GaAs的集成或纳米结构的成核。

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.