First electrical device results are reported for a novel low-Temperature epitaxial deposition process, ultra-clean atmospheric pressure chemical vapor deposition (APCVD). APCVD has been used to grow blanket and selective epitaxial films of Si and Si1-xGex alloys without facets. Films have been grown with controllable n-and p-dopant profiles in reactors which include a commercial 125-200-mm single-wafer processor with integrated preclean capability, a high-Temperature hydrogen preanneal. Large area (105 μ m2) p-n junctions fabricated in epitaxial n-and p-Type Si grown at a temperature as low as 625 degrees C show ideal behavior and low reverse leakage (1 fA/ μ m2) at 5 V. MOS capacitors fabricated in epitaxial Si films show C-V and oxide breakdown characteristics comparable to those of devices fabricated in bulk substrates. These results have promising implications for the implementation of device-quality low-Temperature epitaxy in a CVD reactor without vacuum pumps.