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

第一个资助项目将开发MBE-LEEM系统，结合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的样品交换能力，使复杂样品的成核分析成为可能，提高通量测量的再现性和准确性，提高温度控制的再现性和准确性，增加材料来源的数量，使新材料的增长成为可能，提高安全性，减少系统的停机时间，并提高表面制备过程中的控制。MBE-LEEM的开发将使卡迪夫大学和EPSRC国家III-V技术中心以及世界领先的半导体晶圆公司IQE之间的密切合作成为可能。该系统将用于基础研究，为英国的理论家提供大量关于成核动力学和关键外延工艺的数据，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工艺中的最佳生长参数。MBE-LEEM的扩展能力将通过研究InAs上MnAs的成核来测试，确定ZnC-Blende MnAs的成核条件。Kim等人在2006年展示了厚度低于2个单层的InAs缓冲层上半金属MnAs的成核，但该过程尚未重现，并且没有提供对导致Znc-Blende MnAs的机制的解释。MBE-LEEM将产生MnAs在不同厚度的InAs上成核的视频，突出了成核过程中MnAs晶体结构和形态的演变。半金属半导体的制造可能是自旋电子学发展的关键。后续研究预计在第一个赠款开发项目之后，以分析半金属MnAs的磁性，并将MBE-LEEM应用于外延工艺的其他关键研究，例如GaAs在硅上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.