Mechanisms controlling the phase and dislocation density in epitaxial silicon films grown from silane below 800 °C

We construct a phase diagram for silicon layer growth on (001) Si by hot-wire chemical vapor deposition (HWCVD), for rates from 10 to 150 nm/min and for substrate temperatures from 500 to 800 °C. Our results show that a mixed mono and dihydride surface termination during growth causes polycrystalline growth; some H-free sites are needed for epitaxy. For epitaxial films (T>620 °C), the dislocation density decreases with increasing growth temperature because of reduced O contamination of the surface. The best HWCVD epitaxial layers have dislocation densities of 105 cm−2.