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

Paper SS3+EM-FrM10
Thermal Hydrogen Reactions with Boron-doped Si(100) Surface

Friday, October 29, 1999, 11:20 am, Room 604

Session: Reactions on Semiconductors
Presenter: B. Gong, The University of Texas at Austin
Authors: B. Gong, The University of Texas at Austin
S.K. Jo, Kyung Won University, South Korea
J.G. Ekerdt, The University of Texas at Austin
Correspondent: Click to Email
The reactions of hydrogen with boron-doped Si(100) have been studied with temperature programmed desorption, high resolution electron energy loss spectroscopy and low energy electron diffraction. Recent studies by our group have illustrated that in the boron concentration range from 0.002 to 0.1 monolayer (ML), SiH@sub 2@ (@beta@@sub 2@) formation is greatly suppressed at 400 K. This inability of the H-passivated Si(100) to undergo the 3x1 reconstruction is associated with the subsurface boron-induced bond strain and silicon dimer vacancy defects. At higher boron coverages (0.2-0.5 ML), H@sub 2@ desorption data show a new, broad desorption peak (@beta@@sub 3@) at ~ 400 K in addition to SiH (@beta@@sub 1@) and SiH@sub 2@ states. The @beta@@sub 1@ and @beta@@sub 2@ desorption energies are unchanged by boron. The new H@sub 2@ desorption peak is related to trihydride formation (SiH@sub 3@) on silicon sites that are associated with second layer boron atoms. Both SiH@sub 3@ and @beta@@sub 3@-H@sub 2@ desorption increase with increasing boron coverage. We propose that the enhanced silicon growth rate found during in situ boron doping is related to the new H@sub 2@ desorption channel that has its origin with SiH@sub 3@ formation. Extensive H-induced surface etching is also seen on intrinsic Si(100) surfaces at 180 K. SiH@sub 4@ desorption at ~600 K has been used as an indicator of H-induced etching, where SiH@sub 3@ forms as a result of H atoms breaking Si-Si back bonds; SiH@sub 2@ formation precedes the formation of the SiH@sub 3@ etch product. This surface etching is sharply reduced on lightly boron-doped Si(100) surfaces, which is in good agreement with the result that low coverage boron prevents SiH@sub 2@ formation on Si(100).