AVS 50th International Symposium
    Processing at the Nanoscale Thursday Sessions
       Session PN-ThA

Paper PN-ThA6
Covalent Linkage of Hydrocarbon Moieties and Addition of Organic Functional Groups on Si(111)

Thursday, November 6, 2003, 3:40 pm, Room 317

Session: Molecular Monolayers
Presenter: T. Yamada, RIKEN, Japan
Authors: T. Yamada, RIKEN, Japan
H.S. Kato, RIKEN, Japan
K. Shirasaka, RIKEN, Japan
M. Noto, RIKEN, Japan
M. Kawai, RIKEN, Japan
Correspondent: Click to Email
Deposition of unsaturated hydrocarbon moieties (CH@sub 2@=CH- etc.) on H-terminated H:Si(111)(1x1) surface was performed by Grignard reaction, and addition of boranes and halogens to the C=C double bond was attempted by the methods of wet chemical organic synthesis. The adsorbates formed on Si(111) were investigated by HREELS, AES, etc. in ultrahigh vacuum. Treating H:Si(111) in a tetrahydrofuran (THF) solution of CH@sub 2@=CHMgCl) resulted formation of adsorbates with a major amount of -CH@sub 2@- and a minor amount of CH@sub 2@=, detected by HREELS. The formation of saturated -CH@sub 2@- seems to be due to inter-adsorbate bonding of vicinal CH@sub 2@=CH-groups right after deposition. This parasitic reaction was avoided by using a 1:3 - 5 mixture of CH@sub 2@=CHMgCl and CH@sub 3@MgBr in THF to insert inactive CH@sub 3@- groups among CH@sub 2@=CH- adsorbates. HREELS revealed the ratio of CH@sub 3@:CH@sub 2@=CH in the adlayer was approximately equal to that in the Grignard solution. This sort of CH@sub 2@=CH- moieties diluted in CH@sub 3@- can be useful in reactions with bulky reagents. To realize the terminal hydration of CH@sub 2@=CH:Si(111) into OH-CH@sub 2@-CH@sub 2@:Si(111), hydroboration reaction with a borane reagent 9-BBN was attempted in THF. Deposition of boron was detected by AES, indicating that 9-BBN was bonded by breaking CH@sub 2@=CH bonds. Further attempt to complete the hydration by H@sub 2@O@sub 2@ solution was made, and we are trying to distingish the OH group on the -CH@sub 2@-CH@sub 2@- moiety from OH attached on surface SiO@sub 2@ impurities by HREELS. Addition of HBr on CH@sub 2@=CH:Si(111) was performed by a moderate reaction with HBr in organic solvents. Our goal is to gain a freedom of terminating Si surface with desired functional groups. This is a key technology in grafting polymers and biomolecules such as DNA and peptides to construct intelligent chemically functional system on silicon.