Understanding the vapor–liquid–solid mechanism of Si nanowire growth and doping to synthetically encode precise nanoscale morphology

Abstract

Bottom-up, chemical methods to control the morphology of semiconductor nanostructures are a promising complement to the top-down fabrication techniques that currently dominate the semiconductor industry. Among bottom-up techniques, nanowire (NW) growth using the vapor–liquid–solid (VLS) mechanism has received great attention. In this Highlight article, we review our recent progress toward understanding the microscopic processes that govern VLS NW growth, doping, and dopant modulation. Quantitative measurements of Si NW growth rates and P dopant profiles under a range of synthetic conditions are interpreted with a kinetic analysis of VLS growth that includes the microscopic reactions of incorporation, evaporation, and crystallization. The analysis allows us to identify synthetic conditions that yield both diameter-independent growth rates and abrupt, diameter-independent dopant transitions. The optimized conditions allow precise, sub-10 nm morphology to be encoded along the growth axis of Si NWs, enabling the bottom-up chemical nanofabrication of complex structures that are typically fabricated by high-resolution, top-down lithography.