AVS 54th International Symposium | |
Electronic Materials and Processing | Tuesday Sessions |
Session EM-TuM |
Session: | Molecular Electronics |
Presenter: | A.V. Walker, Washington University in St. Louis |
Authors: | P. Lu, Washington University in St. Louis A.V. Walker, Washington University in St. Louis |
Correspondent: | Click to Email |
We have investigated the deposition of metals on alkanethiolate self-assembled monolayers (SAMs) adsorbed on Au using chemical vapor deposition (CVD) and electroless deposition. This work has important applications in molecular and organic electronics, sensing, biotechnology, photonics and other technologies. Chemical vapor deposition (CVD) is a widely employed technique for the deposition of metals on semiconductor substrates. CVD has not been widely employed to deposit films on organic materials because high temperatures (Tsubstrate > 200 °C) are often required that are not compatible with most organic thin films. However, by exploiting the chemical reactivity of functional groups at the SAM surface it is possible to deposit thin metallic films at room temperature. We demonstrate this method using trimethyl aluminum (TMA). TMA reacts at room temperature with a -COOH terminated SAM to form an Al overlayer, whereas TMA does not react with a -CH3 terminated SAM. We have also investigated the mechanism of electroless deposition of copper on functionalized SAMs using a copper sulphate/formaldehyde reaction. Copper is deposited on -CH3 and -COOH terminated SAMs but not on -OH terminated SAMs. For -CH3 and -COOH SAMs, the deposited Cu is weakly stabilized at the SAM/vacuum interface and so slowly penetrates through the SAMs to the Au/S interface. Further, Cu does not deposit on -OH terminated SAMs because the formaldehyde reacts with the -OH terminal groups rather than reducing the copper.