250 Electronic Properties of a Two-Dimensional Ring-Shaped Kronig-Penney Lattice with a Positional Disorder

We study the effects of a positional disorder in a circular quantum dot array. The potential is modeled by a two-dimensional ring-like Kronig-Penney lattice with a hard-wall radial confinement potential. It is found that even for a small deviation of a barrier from its position in a perfect periodic array, the all energy states in energy spectrum move away from each other by opening energy gaps. This causes to the quenching of Aharonov-Bohm oscillations and results in an enormous reduction in the persistent tunneling current.