AVS 51st International Symposium
    Surface Science Tuesday Sessions
       Session SS-TuP

Paper SS-TuP3
STM Study of Phosphine Adsorption on Si(111)-7x7 Surfaces

Tuesday, November 16, 2004, 4:00 pm, Room Exhibit Hall B

Session: Poster Session
Presenter: J.-Y. Ji, Utah State University
Authors: J.-Y. Ji, Utah State University
T.-C. Shen, Utah State University
Correspondent: Click to Email
PH@sub 3@ reaction with Si(111) surfaces has been studied by Yates et al. and Avouris et al. using a number of analytical techniques including UPS, AES, EELS and ESD in 1990. They concluded that PH@sub 3@ adsorbs dissociatively at 100 K and the surface is chemically inert. We are interested to revisit this system because the P-delta layer in the (111) direction may have interesting technological implications. In this report we present real space images of the PH@sub 3@ adsorption on Si(111)-7x7 at room temperature for various exposures between 0.3-60 L. Applying different sample biases we identify reacted and unreacted adatom sites. Similar to the ammonia adsorption, we find that center adatoms are more reactive than corner adatoms. However, careful analysis shows three different types of reacted sites which can be considered as PH@sub 3@, PH@sub 2@, and H adsorption sites. The coverage counting of the species suggests that most of PH@sub 3@ is dissociatively adsorbed on the surface at initial exposure generating H and PH@sub 2@ adsorption sites, followed by molecular adsorption of PH@sub 3@. Issues involving dissociation and desorption stimulated by electrons, saturation coverage at different substrate temperatures, and surface structures after annealing will be discussed. This work is supported by DARPA-QuIST program under ARO contract DAAD 19-01-1-0324.