AVS 47th International Symposium
    Surface Science Wednesday Sessions
       Session SS2-WeM

Paper SS2-WeM7
Laser Induced Reactivity of Ammonia on Silicon Surface

Wednesday, October 4, 2000, 10:20 am, Room 209

Session: Stimulated Surface Processes
Presenter: T. Gonthiez, GREMI (University of Orleans-CNRS), France
Authors: T. Gonthiez, GREMI (University of Orleans-CNRS), France
P. Brault, GREMI (University of Orleans-CNRS), France
T. Gibert, GREMI (University of Orleans), France
Correspondent: Click to Email
In the field of the growth of materials like Si@sub3@N@sub4@ or AlN, photochemical processes are of a great interest. A study of the reactivity of surface induced by laser of NH@sub3@ on Si(100) is undertaken. Laser fluence and NH@sub3@ pressure are low enough just to realize the first steps of the process. Experimental studies are performed in an ultra-high vacuum chamber. Gaz is introduce by a µ-leakage valve near the surface. A UV laser beam (266/355 nm) is used to activate reactions at gaz-surface interface or to desorb the surface for analysis. Due to initial surface contamination, reactions between NH@sub3@ and Si are self-limiting. Indeed O and C contaminant atoms tie up the surface dangling bonds leading to a passivation layer.@footnote1@ By Auger Electron Spectroscopy, we find that laser irradiation on Si cleans the surface and regenerates the dangling bonds. Analysis of the desorbed species during or after the reaction provides information on reactions at surface. The flying ionic species are directly detected by a quadrupolar mass spectrometer and the neutrals are postionized by a tunable laser. The resonant or non- resonant post-ionization techniques are useful to measure Time-of-Flight distribution of flying species by adjusting the delay between desorption and probe laser. TOF distributions can be fitted by suitable velocity distribution and this allows the determination of kinetic temperature.@footnote2@ This temperature has been shown to be the surface temperature during the laser interaction. Direct measurements of flying ions show several species and mainly Si@sub2@N, Si@sub2@NH, Si@sub2@NH@sub2@ and Si@sub2@NH@sub3@. Comparison between silicon TOF signal with and without NH@sub3@ is expected to give more insight in the nitride bond formation. @FootnoteText@ @footnote 1@Ph.Avouris, F.Bozso, RJ Hamers - J.Vac.Sci.Techno.B 5(5), Sept/Oct 1987; 1387-1392 @footnote 2@ T.Gibert, B.Dubreuil, MF.Barthe, JL Debrun- J.Appl.Phys 74, 3506 (1993).