Increased rate of ozone adsorption on Si(111)-(7x7) with nitrogen preadsorption

We observed by surface second harmonic generation (SHG) that initial the rate of second harmonics (SH) intensity decay during ozone adsorption on nitrogen-preadsorbed Si(111) was four times faster than on clean Si(111)-(7 x 7) because of the adsorption not only of atomic oxygen but also of oxygen molecules released by the dissociation of incident ozone molecules. The temperature dependence of the adsorption rate on nitrogen-adsorbed Si(111) was opposite to that on the clean Si(111)-(7 x 7) surface, but similar to that of molecular oxygen on Si(111)-(7 x 7). With increasing surface temperature, the sticking probability lessened in a similar way to that of molecular oxygen. This suggests that the sticking probability of molecular oxygen released by dissociating ozone molecules increases on nitrogen-adsorbed Si(111). (C) 1998 Elsevier Science B.V. All rights reserved.