Silicon thin film are commonly formed by chemical vapor deposition of silane vapor (SiH4) onto a growling solid Si film. If the following chemical reaction occurs on the surface of the solid Si film, which of the follwing flux relationships are true in the stagnant gas phase above the wafer?  ( SiH₄(g) -> 2H_2(g) + Si(s)),

a) N_SiH4 = -2N_H2,

b) N_SiH4 = 0.5N_H2,

c) N_SiH4 = 2N_H2

d) N_SiH4 = -0.5N_H2

e) N_SiH4 = -N_Si

f) N_SiH4 = N_Si