2 nd case : Interface dominated (tunneling) contact

1. Model of PANI structure Reference : Wojciech Luzny,Maciej Sniechowski « The role of water content for the emeraldine base structure » FIBRES & TEXTILES in Eastern Europe 2003, Vo.11. No. 5 (44) - 7 10 1 - 8 PANI - PU (5% - 50%) 10 2 (mm²) 3 4 us C -9 10 5 6 PANI 100% 8 7 -1 0 10 2 1 10 10 W ( ) R sh Noisy contacts ( Sr and r ) I I =2a l EXCESS 1/f NOISE IN CONDUCTIVE POLYMERS : POLYANILINE/POLYURETHANE (PANI/PU) C. Liang1, G. Leroy1, J. Gest1, L. K. J. Vandamme2, J-L. Wojkiewicz3 1Laboratoire d’Etude des Matériaux et des Composants pour l’ELectronique (E.A.2601), Université du Littoral Côte d’Opale - B.P. 717, 62228 Calais, France 2Eindhoven University of Technology, Department of Electrical Engineering, P.T. 9. 13 P.O. Box 513, 5600MB Eindhoven, The Nederlands 3Ecole des Mines de Douai, Laboratoire des Polymères Conducteurs et CEM, 941 rue Charles Bourseul, 59500 Douai, France E-mail : Liang@univ-littoral.fr Introduction Hooge’s empirical relation for 1/f noise in homogenous semiconductors and metals Rsh : Sheet resistance r : Resistivity of material N : Number of carriers a : Hooge’s parameter µ : Mobility of carriers q : elementary charge n : Density of carriers ( n : Density of carriers ) For the inhomogeneous case, we can calculate a effective value [am]eff : ---------- (*) Experimental results Noise voltage spectral density SV(f) for different currents (sample No. 7) • -Cus versus Rsh for high ohmic samples and low ohmic samples • No influence of the substrate [am]effof PANI-PU films is about 1.2103 m2/Vs. Case of gold : s 5107 S/m [am]eff 3×10-6 m2/W SV(f) @ 4 Hz versus current I (sample No. 7) [am]PANI-PU / [am]Au = 4×108 Discussion Structure of « spaghetti » 1st case : Constriction dominated contact 2nd case : Interface dominated (tunneling) contact and and With Eq.(*), we find With Eq.(*), we find The values of [am]eff / [am] are about 107 ~ 108 and correspond to l ≈ 3-10 µm and 2a ≈ 0,6 nm for constriction dominated contacts or ti = 1 nm for interface dominated contacts. References Conclusion [1] H. Yoshikawa, T. Hino and N. Kuramoto, Synth. Met. 156, 1187 (2006). [2] F.N. Hooge, T.G.M. Kleinpenning and L.K.J.Vadamme, “experimental studies on 1/f noise”, Rep. Prog. in Phys. 44, 479-532 (1981) [3] L. K. J. Vandamme, H. J. Casier, “The 1/f noise versus sheet resistance in poly-Si is similar to poly-SiGe resistors and Au-layers” Eds. R.P. Mertens and C.L. Claeys. no. IEEE Catalog number: 04EX851, pp. 365-368, (2004). Proc. of 34th ESSDERC . IEEE, Piscataway, NJ, USA - A simple proportionality between Cus and Rsh is observed. However, compared with gold films this value in PANI-PU films is very high. - High noise is due to strong current density in the conductive network : Contacts between the molecular chains.