Towards Directed Self-Assembly of Quantum Dot Mesocrystals of Ge/Si Using Focused Ion Beam Patterning

Synthesis and Characterization of Nano-to Meso Scale Ordered Structures in the Si1-xGex Alloy System

“…EBL was ultimately found to produce excellent and highly controllable patterns with good crystalline quality after the Si buffer growth. 121 However, results obtained at the end of that project led us to question whether directed self-assembly of Ge QDs was not actually driven by the imposed morphological pattern. Transmission electron microscopy results suggested that in at least some instances, residual crystal damage at the FIB sites, coupled with the highly constrained thermal budget during MBE cleaning and Ge growth (in order to preserve the fine-scale pattern), may have been the primary bias dictating Ge diffusion and QD site selection.…”

“…Transmission electron microscopy results suggested that in at least some instances, residual crystal damage at the FIB sites, coupled with the highly constrained thermal budget during MBE cleaning and Ge growth (in order to preserve the fine-scale pattern), may have been the primary bias dictating Ge diffusion and QD site selection. 121 Although QD patterning did occur, the incorporated damage made it difficult to subsequently cap the QDs and propagate into the 3 rd dimension so as to form the quantum dot mesocrystal (QDMC). As a result, in the initial experimentation for this project, we reexamined the process flow, particularly to examine whether the use of higher process temperatures would eliminate defectivity while retaining a surface morphological pattern.…”