Progress in group-IV semiconductor nanowires based photonic devices

Despite the dominance in consumer electronics, the use of group-IV semiconductors and their heterostructures is still limited for photonic devices, attributed to the poor emission quantum efficiency in Si and Ge due to their indirect bandgap nature. This has posed serious bottlenecks towards the rapid progress of integrated silicon photonics. However, the recent advances of low-dimensional Si-based heterostructures have shown enormous potential in this direction owing to the significant modification of band structures, leading to improved optical and electronic properties over their bulk counterparts. In this regard, one dimensional Si and Ge nanowires have witnessed an explosion of research interests because of their potential in several promising applications for ultra-compact, silicon-compatible, and functional optoelectronic devices. Novel device architectures integrated with single nanowires and nanowire array geometries have been actively studied and developed. This review presents recent advances in the study of group-IV semiconductor nanowires and their heterostructure-based photonic devices like photodetectors, solar cells and light-emitting diodes etc. Several novel but rational device designs are presented and discussed here, from single nanowire for extraordinary performance to nanowire array heterostructures for large area applications.