Assessing Effects of Near-Field Synergistic Light Absorption on Ordered Inorganic Phototropic Growth

We report herein that synergistic light absorption in the optical near-field enables nanoscale self-organization during inorganic phototropic growth. Se–Te was grown electrochemically under illumination from an incoherent, unstructured light source in geometrically constrained, wavelength scale areas. Despite the limited dimensions, with as few as two discrete features produced in a single sub-micron dimension, the deposit morphology exhibited defined order and anisotropy. Computer modeling analysis of light absorption in simulated structures revealed a synergy wherein light capture in a nanoscale feature was enhanced by the presence of additional adjacent features, with the synergistic effect originating predominantly from nearest neighbor contributions. Modeling moreover indicated that synergistic absorption is produced by scattering of the incident illumination by individual nanoscale features, leading to a local increase in the near-field intensity and consequently increasing the absorption in neighboring features. The interplay between these optical processes establishes the basis for spontaneous order generation via inorganic phototropic growth.