Figure (a) and (b) depict how the growth rate and step coverage depend on the partial pressure of SiCl4, pSi, at 950°C. The samples grown with pSi above 20 Pa have a SC higher than unity, while a lower pSi results in either nearly or non-conformal coatings (SC ≤ 1). To further investigate this effect, depositions were done with pSi varied from 7 to 40