  We report the optical, electrical transport, and magnetotransport properties
of high quality oxygen deficient SrTiO3 (STO) single crystal film fabricated by
pulsed laser deposition and reduced in the vacuum chamber. The oxygen vacancy
distribution in the thin film is expected to be uniform. By comparing the
electrical properties with oxygen deficient bulk STO, it was found that the
oxygen vacancies in bulk STO is far from uniform over the whole material. The
metal-insulator transition (MIT) observed in the oxygen deficient STO film was
found to be induced by the carrier freeze-out effect. The low temperature
frozen state can be re-excited by an electric field, Joule heating, and
surprisingly also a large magnetic field.

Materials Science