Thin Solid Films 405 (2002) 276–289 0040-6090/02/$ - see front matter  2002 Elsevier Science B.V. All rights reserved. PII:S0040-6090 Ž 01 . 01758-8 An approach for fabrication of junctions with Langmuir–Blodgett films incorporated between molecular electrodes V.I. Troitsky *, T.S. Berzina , E. Dalcanale , M.P. Fontana a, a b a Department of Physics and INFM, University of Parma, Viale delle Scienze, 43100 Parma, Italy a Department of Organic and Industrial Chemistry, University of Parma, Viale delle Scienze, 43100 Parma, Italy b Received 6 July 2001; received in revised form 6 December 2001; accepted 6 December 2001 Abstract Langmuir–Blodgett (LB) assemblies composed of monolayers of different compounds alternating in a predetermined sequence are potential candidates for development in the field of nanoelectronics. However, their poor mechanical stability restricts the possibility of fabrication of interconnected electronic elements because LB films can be easily destroyed during the deposition of metal electrodes. In this work, we present a technique for the fabrication of junctions for the electrical characterization of one- component LB films and LB assemblies enclosed between thin molecular electrodes. The molecular electrodes are produced using LB films of a charge-transfer salt. Such an application of these films became possible due to considerable improvements in their conductivity, quality of deposition and stability in comparison with the properties of films of similar compositions studied previously. Lateral patterning of electrodes is carried out by the irradiation of conductive films with an electron beam, which results in the loss of their conductivity. In this way, it is possible to prepare the samples for electrical investigations without any damage to incorporated LB films. The LB films of barium stearate, polycyanoacrylate, mixture of surfactant donor and acceptor, porphyrins, as well as the LB assemblies composed of thin layers of these compounds deposited in various sequences were enclosed between the molecular electrodes and studied. Probable conduction mechanisms are discussed on the basis of obtained data.  2002 Elsevier Science B.V. All rights reserved. Keywords: Langmuir–Blodgett films; Organic conductors; Conductivity; Electrical properties and measurements 1. Introduction Langmuir–Blodgett (LB), Langmuir–Schaefer (LS) techniques w1x, and their modifications w2x allow one to deposit molecular layers of different nature in the required sequence onto solid supports. Thus, little effort would need to be applied to obtain perfectly organized structure and to achieve nanometer scale resolution in the direction normal to film plane. However, for devel- opments in the field of nanoelectronics, appropriate techniques of lateral patterning and interconnection of electronic elements are required. One reason why molec- ular systems based on LB films have not yet found a place in nanoelectronic development is their poor mechanicalstability.Theusualwayofmakingelectrodes *Corresponding author. Tel.: q39-0521-905251; fax: q39-0521- 905223. E-mail address: troitski@fis.unipr.it (V.I. Troitsky). by metal evaporation over a LB film is not suitable because even careful evaporation usually damages at leastafewmonolayersatthetopofthefilm.Inaddition, the further application of ordinary microelectronic proc- essing for the patterning of the metal coating destroys the LB film. Thus, one meets considerable difficulties from this point of view, because to achieve the required functions, the structure must be realized with high precision at the molecular level. Earlier works on electrical studies of LB films w3–5x show that the problem of shorts is extremely challeng- ing, especially if noble metals are used as electrode materials. Geddes et al. w6x have succeeded in the fabrication of metal y LB film y metal insulating junctions using a noble metal as the bottom electrode and mag- nesium as the top one. Recently, Roth et al. w7x, using a carefully elaborated technique, have prepared gold y LB film y gold microsandwiches without shorts. In spite