A spontaneous polysilicon and epitaxial silicon deposition (SPED) process for fabricating high performance submicron devices was developed using Si2H6 as a silicon source gas under low pressure and temperature. SPED was achieved at 8000 Pa and 830 degrees C, even for a 0.2 mu m thick film on a substrate with a 0.5 mu m SiO2 step. The defect density of the epilayer was less than 0.3/cm(2). This SPED layer did not have facets at the transition region.