Nb-doped SrTiO<sub>3</sub> epitaxial thin films have been prepared on (001) SrTiO<sub>3</sub> substrates using pulsed laser deposition. A high substrate temperature (>1000°C) was found to be necessary to achieve 2-dimensional growth. Atomic force microscopy reveals atomically flat surfaces with 3.9 Å steps. The films show a metallic behavior, residual resistivity ratios between 10 and 100, and low residual resistivity of the order of 10<sup>-4</sup>Ωcm. At 0.3 K, a sharp superconducting transition, reaching zero resistance, is observed.