1063-7842/02/4704- $22.00 © 2002 MAIK “Nauka/Interperiodica” 0459 Technical Physics, Vol. 47, No. 4, 2002, pp. 459–464. Translated from Zhurnal Tekhnicheskoœ Fiziki, Vol. 72, No. 4, 2002, pp. 88–93. Original Russian Text Copyright © 2002 by Popok, Azarko, Khaibullin. INTRODUCTION In recent years, conductive polymers have become a popular micro- and optoelectronic material in both sci- entific research and applications [1]. The reason is the advances in the synthesis of new conductive polymers and, hence, their extended potentialities in these areas of technology. Polymer films with the metallic type of conduction have found application as corrosion inhibi- tors, compact capacitors, and antistatic coatings for photographic films and monitor screens. Moreover, the methods of synthesizing polyconjugated systems (which have evolved from the early 1970s) have made it possible to produce polymers of n- or p-conductivity by doping. These materials are used in fabricating organic electronic components, such as light-emitting diodes, transistors, solar cells, storage batteries, etc. [1, 2]. A promising way for producing conductive poly- mers is ion implantation [3–5]. As a result of irradia- tion, a nanostructured system of carbon atoms with conjugated bonds is formed in the implanted layer of a polymer [6]. The conductivity of the implanted layer monotonically rises with dose and may vary within 10 to 15 orders of magnitude [3, 7, 8]. The use of high implantation doses to produce high-conductivity poly- mer layers implies that the process is carried out at increased ion current densities, which cuts the irradia- tion time and improves the process efficiency. However, a high ion current inevitably means a high power being released in the layer irradiated; therefore, this parame- ter is critical for organic materials because of their poor radiation hardness and thermal stability. On the other hand, an increase in the ion current density at a fixed dose raises the conductivity of the implanted polymer layer [9]. Thus, the optimization of the ion implantation conditions for the formation of conductive layers with desired electrical properties seems to be a topical prob- lem in ion-beam modification of polymers. In this work, we study the effect of argon ion implantation on the electrical, paramagnetic, and opti- cal properties of polyimide. Polyimide is a representa- tive of the most thermally stable polymers and allows the ion current density to be varied in wide limits up to 16 μ A/cm 2 . To date, such a high value of the ion current density, as applied to implantation into polymers, has not been reported in the literature. The use of argon ions eliminates the doping effect of impurities and makes it possible to study the purely radiation effect of ions on the polymer. In addition, argon implantation into poly- imide under other process conditions (ion beam param- eters) has been extensively studied [9–11], which allows us to comparatively analyze surface modifica- tions. EXPERIMENTAL The object of investigation was 40-μ m-thick poly- imide films of density 1.43 g/cm 3 (Fig. 1a). The advan- tage of polyimide is that it does not exhibit the transi- tion to the viscoelastic state with increasing tempera- ture. The softening temperature depends on the concentration of imide groups (degree of imidization) s: at s = 1, this temperature exceeds 500 K. The glass The Effect of High Implant Doses and High Ion Current Densities on Polyimide Film Properties V. N. Popok*, I. I. Azarko*, and R. I. Khaibullin** * Belarussian State University, Minsk, 220050 Belarus e-mail: popok@bsu.by ** Kazan Physicotechnical Institute, Russian Academy of Sciences, Kazan, 420029 Russia e-mail: rik@kfti.knc.ru Received September 17, 2001 Abstract—Ar + and Ar 2+ ions with energies of 40 and 80 keV are implanted into thin polyimide films. The implant doses and the ion current densities are varied in a wide range between 2.5 × 10 14 and 1.5 × 10 17 cm –2 and between 1 and 16 μ A/cm 2 , respectively. The effect of the implantation parameters on the electrical, para- magnetic, and optical properties of the ion-modified near-surface polymer layer is studied. It is shown that the radiation-stimulated thermolysis of polyimide and its chemical constitution are responsible for a monotonic growth of the electrical conductivity of the layer with increasing ion current at a given implant dose. When the ion current density is fixed, the conductivity grows stepwise with implant dose, whereas the concentration of paramagnetic centers and the optical transmission of the modified layer decrease. The dependences observed are treated within a model of the structural reconfiguration of the polymer carbonized phase formed during the implantation. © 2002 MAIK “Nauka/Interperiodica”. SURFACES, ELECTRON AND ION EMISSION