半导体纳米线在电子、光电子以及传感器件中有着广泛的应用前景。III-V族半导体纳米线因其具有高发光效率（直接带隙发光）和高电子迁移两个优点而备受关注。通过改变III-V族纳米线的组分，可以调节其带隙的宽度，从而可以实现不同光谱波段的应用。半导体纳米线另一个迷人的特点是可以实现不同材料的混合外延生长，而这是普通薄膜材料所很难达到的。然而传统的纳米线生长需要用到金属催化剂，金属催化剂如金的使用会形成深能级陷阱，污染半导体纳米线，从而严重影响光电子器件的性能。因此纳米线的无催化剂外延生长就显得极为重要。本项目拟探索无催化剂的InAsSb纳米线在GaAs衬底上的高质量外延生长，在实现了此目标的情况下，利用申请人之前硅基GaAs高质量外延生长的丰富经验，进一步实现无催化剂InAsSb纳米线在硅衬底上的高质量生长。该研究工作的顺利开展和完成将推动硅基中红外光电子器件大规模集成的发展。

Semiconductor nanowires are leading candidates for future applications in a wide variety of electronic, photonic, and sensing devices. III-V compound semiconductor nanowires have a number of potential physical advantages over elemental semiconductor nanowires including high mobility and direct bandgap. Furthermore, the magnitude of the bandgap can be modulated by exploiting ternary compound semiconductors, allowing the creation of heterostructure nanowires with selective optical energies. .One of the most intriguing features of semiconductor nanowires is the ability to realize epitaxial growth of material combinations not realized in bulk or layer growth. Of particular interest is the growth of group III-V semiconductors on Si substrate, exploiting the mature Si technology, the ability of large substrates in combination with the superior optoelectronic and electronic properties of III-V compounds. Metal seed particles are widely used for nanowire growth, preferentially Au nanoparticles. For the integration with Si technology, this is problematic due to Au forming deep level traps in Si. Therefore, several growth schemes avoiding foreign metal seed particles have been developed. A variety of mechanisms of catalyst-free growth have been suggested, but surprisingly little systematic work has been performed to establish these mechanism firmly, and more importantly, to determine the actual relevant one for wire nucleation. Here, we propose the catalyst-free InAsSb direct epitaxial growth mechanism on GaAs/Si virtual substrate for mid-IR applications, which can be used as highly integrated, low cost Si-based mid-IR photonic devices, such as lasers and photodetectors.