Fabrication, characterization, and applications of nanometer-scale features within organomercaptan self-assembled monolayers /
Nanometer-scale features in organomercaptan self-assembled
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| Format: | Thesis Book |
| Language: | English |
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[Place of publication not identified] :
[publisher not identified] ;
1997.
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| Online Access: | http://proxy.library.tamu.edu/login?url=http://proquest.umi.com/pqdweb?did=739887921&sid=1&Fmt=2&clientId=2945&RQT=309&VName=PQD |
| Summary: | Nanometer-scale features in organomercaptan self-assembled monolayers (SAMs) on Au(ill) substrates were prepared by three methods: electrochemical enhancement of adventitious defects, electrochemical enhancement of template-molecule- induced pores, and scanning tunneling microscopy (STM)- induced patterning. The resulting features were characterized by electrochemistry, scanning electron microscopy (STM), and electrochemical STM (ECSTM). Finally, we applied STM-induced patterning methods to lithographic fabrication of features with critical dimensions < 100 nm. The results indicate that n-alkanethiols SAMs form excellent lithographic resists and barrier layers to electron and mass transfer. Further, the nanometer-scale features act as nanometer-size electrodes. Measurements of the physical dimensions of nanometer-scale features by STM can be combined with microelectrode theory to calculate a value for the limiting current. Comparison of this value with that obtained directly from conventional electrochemistry provides qualitative agreement. From in-depth studies of the mechanistic aspects of STM- induced patterning of organomercaptan SAMs we determined that this process is controlled by a complex combination of parameters defined by both the instrument and the chemical and physical properties of materials in the vicinity of the tip. In particular, the patterning is dependent on the magnitude and polarity of the gap bias, the Coulomb dose, and the composition of the gap. From this information we propose a detailed multi-step model for STM-induced removal of nalkanethiol SAMs from Au surfaces. The model is partially based on our observation that high tip bias (> -+2.30 V) results in removal of SAMs by Faradaic electrochemical processes in which the n-octadecyl mercaptan monolayer is: (1)disrupted by the tip, (2) electrochemically desorbed, and (3)removed by the scanning action of the tip. Further, we determined that at biases above a second threshold (-+4.0 V) the patterning becomes irreproducible because the patterning mechanism changes to field desorption or evaporation from the surface. Finally, we showed that combining STM-induced patterning with selective low-temperature chemical vapor deposition of Cu allows metalation of features with critical dimensions as small as 100 nm. |
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| Item Description: | Vita. "Major Subject: Chemistry". |
| Physical Description: | xvi, 222 leaves : illustrations ; 28 cm. Issued also on microfiche from University Microfilms Inc. |
| Bibliography: | Includes bibliographical references: pages 202-219. |