The formation of the domain structure by electron beam irradiation in thermally depolarized Ce-doped strontium barium niobate single crystals with free surface and surface covered by a dielectric layer has been studied. The dependences of the domain sizes and domain depth on the irradiated dose have been measured. The circular shape of the isolated domains was obtained. The isotropic domain growth was attributed to step generation at the wall as a result of merging with the residual nanodomains which existed after thermal depolarization. The linear dose dependence of the switched area was attributed to the screening of the depolarization field by the injected charge. The electrostatic interaction of the approaching charged domain walls was revealed. The better quality of the domain patterns was achieved in the samples with electron localization in the dielectric layer. The obtained results can be applied for the creation of precise domain patterns with arbitrary orientation and shape to produce nonlinear optical devices with improved characteristics.