The low and high frequency dielectric properties of epitaxial SrTiO3 (STO) thin films deposited on LaAlO3 are presented. The effects of in situ ozone annealing during the early stages of deposition were explored. X-ray diffraction results indicated that the ozone treatment resulted in more symmetric and sharper diffraction peaks. In addition, the peaks for the ozone treated samples were shifted in 2 theta towards values approaching the bulk. The dielectric constant of the ozone treated samples increased from 275 at room temperature to 1175 at 22 K (measured at 100 kHz). The effective loss tangent of the device remained between 1 x 10(-4) and 1 x 10(-3) down to 100 K, where it began to increase. These properties were far superior to those films deposited without ozone. For high frequency measurements, coplanar waveguide structures with a centerline width of 20 and 40 mum wide gaps were patterned into YBa2Cu3O7 films deposited on top of the 0.5 mum thick STO. For the ozone treated films, Q values of up to 70% greater were achieved at 4 GHz and 75 K with little effect on the frequency modulation (compared to films deposited without ozone).