The paper demonstrates that the technology of plasma-assisted molecular beam epitaxy (PA MBE) can be used to form epitaxially overgrown GaN, n-GaN, and n+-GaN contact layers with a high structural quality on virtual GaN/c-Al2O3 substrates under Ga-enriched conditions at relatively low growth temperatures of ~700 °C. It was shown that the initial stage of growth of the contact layers was accompanied by effective filtration of dislocations threading from the buffer GaN layer of the virtual substrate formed by MOCVD. The values of residual stresses calculated using the data of Raman microspectroscopy indicate a high structural quality of GaN, n-GaN, and n+-GaN contact layers regardless of the level of silicon doping. The contact resistance reduced to the pad width determined using the transmission line method for the structure with n+-GaN contact layer was ~0.11 Ohm·mm and for the n-GaN contact layer it was ~0.5 Ohm·mm.