Effect of weak positional disorder on the miniband structure of spherical quantum dot chains
A theoretical framework is developed for the electron miniband structure in one-dimensional chains of spherical quantum dots subjected to weak positional disorder. Within the tight-binding approximation combined with the effective-medium approach, the stochastic fluctuations of the inter-dot spacing are mapped onto the renormalization of the key Hamiltonian parameters: the hopping integral $ B $, the overlap integral $ Q $, and the on-site energy shift $ M $. Analytical expressions for these disorder-renormalized parameters are derived by performing an ensemble average over a narrow Gaussian distribution of positional deviations ($ σ\ll a $). The resulting generalized dispersion relation shows that weak positional disorder causes a broadening of the minibands. Specifically, for typical fabrication fluctuations $σ= 0.1\,a $, the miniband width increases by 8-12\% (depending on the mean inter-dot distance $a$). At the same time, the sensitivity of the miniband width to disorder decreases rapidly with increasing lattice period due to the exponential decay of the electron wave functions. In the considered weak-disorder regime, the Anderson localization length significantly exceeds the lattice constant, so the miniband states remain delocalized.