Redesigning silicon via surface chemistry

초록

This presentation will provide an overview of our efforts to understand the fundamental chemical information underlying semiconductor nanowire growth. The vapor-liquid-solid (VLS) method, where the "liquid" catalytic droplets collecting atoms from vapor precursors build the solid crystal layers via supersaturation, is a ubiquitous technique to synthesize 1-dimensional nanoscale materials. However, a lack of fundamental understanding of chemical information governing the process inhibits the rational route to the structural programming. Long-standing challenges in the control of growth orientation- so called "kinking", dopant profile, and atomic stacking sequence restrict the accessible property space and highlight the pitfalls of an overreliance on empirical process optimization. By combining the in situ or operando spectroscopy with post-growth high resolution electron microscopy, we show the strong correlation between the surface chemical species concentration and nanowire structures. More specifically, the critical role of surface adsorbed hydrogen, generated from the decomposition of Si2H6 precursor on the growth orientation change and the planar defects formation in Si nanowire is demonstrated. These results ultimately provide the insights to control nanowire structure with atomic scale precision.