In this work, we evaluate the effect of the novel symmetric multicycle rapid thermal annealing (SMRTA) process on both Mg ion implanted and non-implanted thick unintentionally doped GaN drift layers for vertical power devices. The typical p-type behavior and restoration of implant damage are observed in implanted samples, but on non-implanted samples a reduction in background carrier concentration and associated reduction in leakage current and increase in breakdown voltage is observed. This indicates that the capping/annealing process itself is not detrimental to the crystal, and the annihilation of native point defects in the process has beneficial effects for device structures.