We have used extended-range MISC(V)measurement to carry out a preliminary study of the effect of the variation of epitaxial Si growth parameters on interfactial charge in ion implantation doped silicon-on-sapphire (SOS) capacitors. Our results to date show that 1) both the magnitude and the ploarity of the interfacial charge are affected by the Si growth rate; 2) the magnitude charge are affected by prefiring of the substrate in hydrogen; 3) at room temperature, some annealing of the radiation-induced charge takes place in less than 20 h, and virtually complete annealing takes place within one month; 4) the radiation. The implications for the solution of the back-channel leakage problem are discussed.