Opto-electronic properties of twisted bilayer graphene quantum dots

摘要: Abstract The electronic and interband optical properties of vertically coupled stacked graphene quantum dots are investigated using the tight-binding method. Both zigzag armchair edge configurations taken into account. In particular, effect geometrical shape (triangular or circle-like) and, most prominently, angle twisting between layers is mainly addressed. response analyzed from calculated imaginary part dielectric function. It found that absorption threshold highly dependent on dot size geometry: For triangular bilayer gap exhibits a moderate increase for smaller angles twisting, structure behaves as an intermediate to wide semiconductor; whereas small systems in which causes appearance zero-gap states associated with variation HOMO LUMO resulting breaking zero-energy degeneracy. latter case, it shown low-energy transitions those responsible main structures indicates possible applications THz optoelectronics. Circular chosen commensurable also show stronger thresholds. A particular feature appearing this case presence Bravais-Moire patterns two-dimensional probability density distributions large enough radii.