AVS 47th International Symposium
    Semiconductors Tuesday Sessions
       Session SC+EL+SS-TuM

Paper SC+EL+SS-TuM11
Photon-activated Electron-Transfer-Reaction Surface Modification of GaAs(001)

Tuesday, October 3, 2000, 11:40 am, Room 306

Session: Compound Semiconductors
Presenter: N. Camillone III, Columbia University
Authors: N. Camillone III, Columbia University
K.A. Khan, Columbia University
J.A. Yarmoff, University of California, Riverside and Lawrence Berkeley National Laboratory
R.M. Osgood, Jr., Columbia University
Correspondent: Click to Email
UHV methods for adjusting the reconstruction and composition of the top layer of atoms on a semiconductor surface are expected to have important implications for precise control of growth surfaces and surface reactions. In this talk we will describe a transformation of the surface reconstruction resulting from a photoinduced electron transfer reaction occurring thereupon. We have carried out preliminary studies which demonstrate that variation in photon exposure and thermal treatment allows the surface reconstruction to be controllably adjusted from the Ga-rich c(8x2) to the (4x6), (3x1) and As-rich c(2x8) terminations. The modification of the reconstruction is the result of a modification of the surface stoichiometry due to the extraction of surface Ga atoms as a result of reaction with bromine. The bromine is produced at the surface by photoinitiated dissociative electron attachment to methyl bromide molecules physisorbed in a single monolayer at ~ 90 K. Subsequent to the photoinduced surface reaction, the gallium is removed by annealing to desorb a gallium bromide product. A comparison of the results obtained with low energy electron diffraction, temperature programmed desorption and energy-resolved photofragment angular distribution measurements shows that the most As-rich surface obtained by our technique is identical in structure to that of a control surface prepared using the standard iodine thermal reaction method. In principle, the use of this photon-activated reaction, and others like it, could allow for precise patterning of the surface structure based on control of photon or electron exposure, molecular coverage, thermal treatment and lateral patterning of the incident photon or electron beam.