The crystalline quality of 0.3‐&mgr;m‐thick silicon on sapphire structures has been improved by double solid phase epitaxy of germanium‐implanted material. This regrowth technique increased the mobility with 70–100% in phosphorus‐ and boron‐doped films, respectively. The depth distribution of germanium induced donors was measured by capacitance‐voltage profiling on diodes made in preamorphized bulk silicon and the energy distribution in the band gap was investigated with deep level transient spectroscopy. It was shown that the main part of the germanium implantation induced defects could be removed by a high‐temperature annealing treatment.