It is demonstrated that deep states in silicon on sapphire (SOS) films can be evaluated by transient-current spectroscopy (TCS). In the TCS spectra, a broad peak extending over 100–200 K was observed for the 6000-Å-thickn-type SOS film. Assuming the value of capture cross section to be10−15cm2and independent of temperature, the density distribution of deep states was estimated. The density distribution shows a peak of1.2×1012cm−2 eV−1atEC−0.25eV. Raman backscattering spectroscopy was also performed to evaluate the stress in the silicon film. It was concluded that the defects detected by TCS should be caused by the compressive stress of6.2×108Pa in the silicon film. ©1997 American Institute of Physics.