Selective epitaxy of InP nanocrystals on Si nano-tips for hybrid graphene/InP/Si photodetectors

The monolithic integration of III-V semiconductors having superior (opto-)electronic properties onto the mainstream Si technology platform presents a long-standing vision for scientists and engineers owing to a variety of device applications, which is, however, hindered by the fundamental materials issues such as lattice and thermal expansion mismatch and the formation of antiphase domains. InP could open new avenues for the realization of novel devices such as high mobility transistors in next generation CMOS (as a substrate) or efficient lasers for light distribution in silicon photonics circuitry. We presented here a CMOS compatible Si nanotip method to epitaxially grow high quality InP nanocrystals (NCs) with no threading defects, obtaining thus substrate-like optoelectronic properties on highly heterogeneous Si substrates. Fully relaxed, site and size controllable InP NCs were selectively grown on Si-tip wafers due to an In-desorption dominated growth mechanism. Defects like micro-twins and stacking faults existing in InP NCs do not severely degrade the optical properties. A prototype hybrid photodetector based on graphene/InP/Si device was realized and shows promising photodetection. The results demonstrated in this work will open up exciting opportunities for the heteroepitaxy of highly-mismatched III-V materials and thus the integration of various high performance (opto-)electronic hybrid devices on Si.