Miniband formulation of bilayer type II Ge/Si quantum dot superlattices

This article presents a computational study on the impact of layer distance on the miniband formulation and density of state under different quantum dot structural parameters-height, interdot space-in a bilayer and well-aligned Ge/Si quantum-dot array. The miniband bandwidth, energy and effective bandgap is tunable by introducing an additional quantum dot layer. When the vertical distance between layers is smaller than 2.0 nm, the individual band structure of each layer will separate and couple into a broader bandwidth. The effective bandgap decreases since the highest excited states, with broader bandwidth, mix with and become continuous energy levels.