高质量窄禁带半导体/超导体异质结纳米线网络的原位分子束外延生长及输运性质

基于Majorana费米子的拓扑量子计算是解决量子计算机纠错问题的重要方案。发展高质量窄禁带半导体/超导体异质结纳米线网络的制备技术，是在窄禁带半导体/超导体体系实现Majorana束缚态并进行编织操作等研究的前提。只有国外少数几个单位掌握了该技术，国内还处于技术空白。本项目拟利用分子束外延，在已实现高质量InAs/Al等异质结纳米线原位外延基础上，针对InAs和InSb材料体系，通过改变衬底晶向、调节生长参数及开展选区外延等发展窄禁带半导体/超导体异质结纳米线网络的原位外延技术；此外，基于立式单晶InAs及InSb纳米片，开展纳米片侧面超导金属的原位外延，结合微纳加工，制备窄禁带半导体/超导体异质结纳米线网络。研究不同方式制备的异质结纳米线网络的输运性质。制备出界面达原子级平整且具有硬超导能隙的异质结纳米线网络，为基于该体系的Majorana费米子探测及编织操作提供材料基础和技术积累。

Majorana fermions-based topological quantum computation is an important scheme for error correction of the quantum computer. A basic requirement for obtaining Majorana bound states and realizing braiding in the semiconductor-superconductor system is developing growth techniques of high-quality narrow bandgap semiconductor-superconductor heterostructure nanowire networks. These techniques have only been realized in quite a few foreign universities supported by Microsoft company, and they are absent in China. This project focuses on InAs and InSb and aims at the in situ molecular-beam epitaxy growth of narrow bandgap semiconductor-superconductor heterostructure nanowire networks by changing substrate orientations, tuning the growth parameters and developing the selective-area growth technique etc. based on the successful in situ growth of high-quality narrow bandgap semiconductor-superconductor heterostructure nanowires such as InAs-Al. We also plan to in situ grow superconductor metals on the facets of the free-standing single-crystalline InAs and InSb nanosheets, respectively, and then develop processing techniques of high-quality narrow bandgap semiconductor-superconductor heterostructure nanowire networks on these single-crystalline nanosheets using the (micro-) nano-machining technology. A comprehensive transport property characterization will be performed on these heterostructure nanowire networks grown by different manners. Based on the optimization of material quality and the transport properties, we attempt to grow the narrow bandgap semiconductor-superconductor nanowire networks with the interfaces of atomic scale uniformity and hard superconducting gaps. It is expected that this project can provide material basis and technical guidance for detecting and braiding Majorana fermions based on the system of narrow bandgap semiconductor-superconductor heterostructure nanowire.