(262g) Modeling of Quantum Dot Pattern Formation on Pit-Patterned Semiconductor Substrates

Self-assembly of ordered nanostructures plays an important role in the development of nanofabrication strategies that can integrate ordered patterns of nanostructures, such as nanorings and quantum dots of uniform size, into electronic devices. Due to the unique nature of electronic confinement, such nanostructures exhibit outstanding properties that enable a broad range of applications in electronic, optoelectronic, sensing, and magnetic data storage technologies. Recent experimental studies have demonstrated the formation of ordered Ge nanoring and quantum dot patterns on the surfaces of Ge thin films grown epitaxially on pit-patterned Si{100} substrates. Here, we aim at establishing a fundamental understanding of the kinetics underlying the formation of confined quantum structures in coherently strained epitaxial thin films grown on pit-patterned semiconductor substrates.

We develop an atomistically informed, three-dimensional continuum-scale kinetic model for monitoring the surface morphological evolution of coherently strained heteroepitaxial thin films that captures the morphological response of epitaxially grown Ge thin films on pit-patterned Si{100} substrates. The model accounts for curvature-driven atomic diffusion on the film surface, biaxial lattice misfit strain in the film, and the wetting potential between the film and the substrate. Self-consistent dynamical simulations based on our model show formation of complex nanostructures on the epitaxial film surface, including nanorings at the rims of pits, a single quantum dot at the center of a pit, as well as multiple quantum dots inside rectangular pits, consistent with the nanostructures observed in the experiments. Our simulation results reproduce the variation in the formed nanostructural features observed experimentally by properly varying the key experimental parameters, namely, the pit size and the pit geometry. Our modeling and simulation study sets the stage for designing systematic experimental protocols toward precise control of complex nanoring and quantum dot patterns forming on surfaces of epitaxially grown coherently strained semiconductor thin films.