Modeling Catalyst-Free Growth of III-V Nanowires: Empirical and Rigorous Approaches

Catalyst-free growth of III-V and III-nitride nanowires (NWs) by the self-induced nucleation mechanism or selective area growth (SAG) on different substrates, including Si, show great promise for monolithic integration of III-V optoelectronics with Si electronic platform. The morphological design of NW ensembles requires advanced growth modeling, which is much less developed for catalyst-free NWs compared to vapor-liquid-solid (VLS) NWs of the same materials. Herein, we present an empirical approach for modeling simultaneous axial and radial growths of untapered catalyst-free III-V NWs and compare it to the rigorous approach based on the stationary diffusion equations for different populations of group III adatoms. We study in detail the step flow occurring simultaneously on the NW sidewalls and top and derive the general laws governing the evolution of NW length and radius versus the growth parameters. The rigorous approach is reduced to the empirical equations in particular cases. A good correlation of the model with the data on the growth kinetics of SAG GaAs NWs and self-induced GaN NWs obtained by different epitaxy techniques is demonstrated. Overall, the developed theory provides a basis for the growth modeling of catalyst-free NWs and can be further extended to more complex NW morphologies.

Automated summary

In this study, an empirical approach for modeling the growth of untapered catalyst-free III-V nanowires is presented and compared to a rigorous approach based on diffusion equations. The step flow occurring on the sidewalls and top of the nanowires is studied, and the general laws governing the evolution of nanowire length and radius are derived. The model shows good correlation with the growth kinetics of SAG GaAs nanowires and self-induced GaN nanowires. This developed theory provides a basis for growth modeling of catalyst-free nanowires and can be extended to more complex nanowire morphologies.