INCREASED RATE OF OZONE ADSORPTION ON SI(111)-(7X7) WITH NITROGEN PREADSORPTION

We observed by surface second harmonic generation (SHG) that initial t he rate of second harmonics (SH) intensity decay during ozone adsorpti on 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 b ut also of oxygen molecules released by the dissociation of incident o zone molecules. The temperature dependence of the adsorption rate on n itrogen-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 less ened 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 Elsev ier Science B.V. All rights reserved.