AVS 46th International Symposium
    Surface Science Division Friday Sessions
       Session SS3+EM-FrM

Paper SS3+EM-FrM11
Impact of Surface Structure on the Arsine Adsorption Kinetics on GaAs and InP (001)

Friday, October 29, 1999, 11:40 am, Room 604

Session: Reactions on Semiconductors
Presenter: Q. Fu, University of California, Los Angeles
Authors: Q. Fu, University of California, Los Angeles
L. Li, University of California, Los Angeles
C. Li, University of California, Los Angeles
D. Law, University of California, Los Angeles
R.F. Hicks, University of California, Los Angeles
Correspondent: Click to Email
Arsine adsorption on the gallium-rich GaAs (001) (4x2) reconstruction and on the indium-rich InP (001) (2x4) reconstruction has been studied by internal-reflection infrared spectroscopy and scanning tunneling microscopy. It was found that AsH@sub 3@ adsorption on the (4x2) follows an autocatalytic mechanism, with the rate proportional to the fraction of occupied and vacant sites. By contrast, AsH@sub 3@ adsorption on the (2x4) follows a Langmuir adsorption mechanism, with the rate depending only on the fraction of vacant sites. We attribute these differences in the reaction kinetics to the impact of the semiconductor surface structure on the adsorption mechanism. The GaAs (4x2) reconstruction is terminated with 3 gallium dimers per unit cell, while the InP (2x4) contains one In-P heterodimer, and 4 In dimers per unit cell. An arsine molecule dissociatively adsorbs onto the group III dimers and transfers hydrogen to a group V dimer site. On the GaAs (4x2), only a few of these latter sites are present, and more are created by adsorption, so the reaction is autocatalytic. Conversely, on the InP (2x4), the latter sites are readily available, and Langmuir adsorption occurs. The decomposition mechanisms of arsine on these surfaces will be discussed in detail at the meeting.