The structure of the chaotic potential caused by the electrostatic field of charged dislocations in group III-nitride heterojunctions is investigated. Taking into account the spatial dispersion of the dielectric response of a two-dimensional electron gas, the amplitude and scale of the chaotic potential in the junction plane are determined. It is shown that the parameters of the chaotic potential depend on the density of surface states and the concentration of dislocations. © 2021, Pleiades Publishing, Ltd.