5526
J . Am. Chem. SOC.1987, 109, 5526-5528
shorter than the C-Se bond lengths of 1.97 A found in the salt of 2, causes the distortions in 1, n = 3, to he quantitatively larger. For example the pyramidalization angles a t the double-bonded carbons are predicted lo be 30' and 3 3 O in 1, n = 3." Therefore, the finding that 2 is an isolable molecule, stable at room temperature, makes the hydrocarbon (1, n = 3) an eswially attractive target for synthesis and study Acknowledgment. We thank the National Science Foundation for support of this work. Supplementary Material Available: Crystallographic data for the methylselenonium triflate salt of 2--crystal data and summary of data collection and refinement, fractional coordinates and thermal parameters, anisotropic thermal parameters, interatomic distances, and interatomic angles ( 5 pages). Ordering information is given on any current masthead page. (22) There is some evidence that MM2 may tend to overestimate the
amount of pyramidaliration in 1. n = 3.'
l'rn~r;~
b=A/
ID
Preparation and Characterization of Molecule-Based Transistors with a 50-nm Source-Drain Separation with use of Shadow Deposition Techniques: Toward Faster, More Sensitive Molecule-Based Devices
1-
Au'
&an
(b) Figure 1. (a) Dcvicc structure reported here and (b)
(a) AS FABRICATED E. Tracy Turner Jones, Oliver M. Chyan, and Mark S. Wrighton?
AU
Department of Chemistry Massachusetts Institute of Technology Cambridge. Massachuseits 02139 Received April 14. 1987
(b) Au SHADOWED AU
We report preparation and characterization of the moleculebased transistor in Figure l a having a significantly smaller (-50 nm vs. 1.5 pm) source-drain separation and smaller ( I W 4 vs. IO-" mol) amount of redox polymer comprising the channel compared to previously reported' devices like that in Figure Ib. The new microstructure with 50-nm source-drain spacing can be prepared by shadow deposition techniques' avoiding the need for X-ray3 or e- beam' lithography. The 50-nm spacing for the open-faced sandwich structure rivals the smallest spacing achievable with conventional sandwich arrangements of electrode/polymer/ electrode used to demonstrate the first "bilayer" assemblies? Figure 2 shows the sequence used to prepare the new microstructure in Figure la. The procedure begins with a Si,N,-coated
(c) SiO,
SHADOWED Au
(d) POLYMER MODIFIED Polymer
(I) (a) Kittlesen. G . P.; White. H. S.;W"ghton. M. S. J. Am. Chem. Soe. 1984. 106. 7389. Ib) Paul. E. W.: Ricm. A. J.: Wriehtan. M. S. J.~Phvr.~ ~ _ Cheh. 1985. 89, 1441. (c)Thack&y, J.'W.;~White,H. S.; Wrighton,~M. S. J. Phyr. Chem. 1985. 89. 5133. (d) Loftan. E. P.; Thackeray, J. W.; Wrighton. M. S. J. Phys. Chem. 1986. 90,6080. (2) (a) Dean. R. H.; Matarese, R. I. IEEE Tram. Electron Devices 1915. ED-Z1,358. (b) Dolan. G . J. Appl. Phys. Lett. 1911,31. 337. ( c ) Speidell, J. L. J. Voe. Sei. Teehnol. 1981. 19,693. (d) Holdeman. L. 8.: Barber. R. C ; Abita. J . L. J . Vor. Sn. Tmhnoi 1985. 83. 956. ( 3 ) (a) blmdcrr. D. C . Appl. Ph, I. IP(( 1980, 36.93. (bJ Chow S Y ; Smith. H I.. AntOnmdi,. D .A J . Poc Sri Terhnol 1985. 83. 1587. i, d, Smith, H. 1. J . Vat. Sci. Techno/. 1986, B4, 148. (4) (a) Crewc. A. V. J . Voe. Sei. Teehnol. 1919. 16, 255. (b) Howard, R. E.; Hu, E. L.;Jackel, L. D.;Grabbc, P.; Tcnnant. D.M. Appl. Phys. Left. 1980.36.592. (c) Dir. C.: Flavin. P. G.: Hendv. P.: lone. M. E. J . Voc. Sei. Teehnol. 1985. B3, I 3 i . id) Em&, F.;'Gamd,'K.;'Namba,S.;Samoto. N.; Shimm. R Jpn J . Appl. Phyr 1985. 24, L809 c 5 l (a) Pickup. P G ; M u m ) . R. W. J . Am Chcm S M 1983, fOS.4510 ( b l Pckuo. P G : Lcidncr. C R.. Dcnirevich. P : M u r r a \ . R W J El
