Gate self-assembled monolayer

Collet J, Tharaud O, Chapoton A, Vuillaume D (2000) Low-voltage, 30 nm channel length, organic transistors with a self-assembled monolayer as gate insulating films. Appl Phys Lett 76 1941-1943... 

Collet, J. Vuillaume, D. Nano-field effect transistor with an organic self-assembled monolayer as gate insulator. Appl. Phys. Lett. 73, 2681-2683 (1998). 

Kubiak and coworkers used STM in an ultra-high vacuum environment to study the conductance through self-assembled monolayers of simple Jt-conju-gated, thiol-terminated molecules on gold [21-23, 59] Early work, which focused on the p-xylyldithiol 82 monolayers [22, 23], was later expanded to include also short oligophenylenes (OPs) (81 and 83) that were terminated at either one or both ends by thiol or isocyanide groups [21]. Based on this work, a relatively simple model was presented to account for the observed conductance spectra of the junctions [22],... 

Bottom-gate, top-contact (Fig. 4.2a) and a bottom-gate, bottom-contact (Fig. 4.2b) TFT configurations are used to evaluate the FET performance of our semiconductors. The devices are built on an n-doped silicon wafer (gate electrode) with a 100-nm thermal silicon oxide (SiC>2) dielectric layer which is modified with a self-assembled monolayer of octyltrichlorosilane (OTS-8) to promote molecular ordering in the semiconductor layer. For the top-contact device the semiconductor layer ( 20-50 nm) is deposited on the OTS-8-modified SiC>2 surface by spin coating. A... 

The device yield of TFTs with molecular gate dielectrics would be expected to be low, because of defects in the thin self-assembled monolayer arising from the imperfect surface of the evaporated aluminum bottom electrode. Results obtained on... 

The TFT fabrication process on glass substrates starts with 100 nm of Cr for the gate metal, and is followed by a PECVD 200 nm thick Si3N4 dielectric with a 30 nm thick SiC>2 surface layer. The source drain metal is Cr/Au. Each of these layers is patterned using printed wax masks and chemical etching, steps a to d in Fig. 11.8. The surface is modified with a solution deposition of a self-assembled monolayer of octyltrichlorosilane (OTS-8) before inkjet printing deposition of the semiconductor. It has been shown that the OTS-8 layer affects the structural order of PQT-12 in thin films, improving the performance of the TFT [23]. Encapsulation and possibly other subsequent layers may be needed on the TFT, but these are not discussed here. 

Gate sites may be formed in self-assembled monolayers when the layers are prepared on surfaces in the presence of a template which is subsequently extracted (Fig. 18.7). The principle was first described by Sagiv using visible absorption spectroscopy to determine the uptake of cyanine dyes [106]. Yamamura and co-workers... 

Very recently Lahav et al. [116] used a photochemically cleavable template to introduce gate sites into an alkanethiol self-assembled monolayer on a gold electrode. The electrode showed an enhanced amperometric response to the electroactive template, compared with an electrode with a monolayer without gate sites. 

Common to many of these studies is that selectivity, where it has been examined at all, has only been reported between the template and species of quite different charge or polarity. It is difficult in such cases to attribute selectivity to the geometry of the gate sites rather than changes in the bulk properties of the electrode surface. Gate sites in self-assembled monolayers provide a simple method for the modification of sensor surfaces. However, the degree of selectivity obtainable in this way. 

Walter, D. G., Campbell, D. J., and Mirkin, C. A. Photon-gated electron transfer in rwo-component self-assembled monolayers. /. Phys. Chem. B 1999,103, 402-405. 

Avila, A., Gregory, B.W., Niki, K., and Cotton, T.M. (2000) An electrochemical approach to investigate gated electron transfer using a physiological model system cytochrome c immobilized on carboxylic acid-terminated alkanethiol self-assembled monolayers on gold electrodes. Journal of Physical Chemistry... 

U., Utesch, T., Mroginski, M.A., Hildebrandt, P., and Weidinger, I.M. (2008) Gated electron transfer of yeast iso-1 cytochrome c on self-assembled monolayer-coated electrodes. Journal of Physical Chemistry ,112,15202-15211. 

Section 20.2 presents the sample geometries and preparation techniques, and Sections 20.3 and 20.4 summarise oiu findings for bottom and top contact geometries, respectively. In the latter case, we compare gate oxides with and without application of an OTS self-assembled monolayer. The main achievements of the present work are summarised in Section 20.5. 

Park, Y.D., Kim, D.H., Jang, Y, Hwang, M., Lim, J.A. and Cho, K., Low-voltage polymer thin-fihn transistors with a self-assembled monolayer as the gate dielectric, Appl. Phys. Lett, 87, 243509, 2005. 

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