1 F NOISE IN CONDUCTING LANGMUIR-BLODGETT-FILMS/

Measurements of spectral characteristics of electric noise in conducti ng Langmuir-Blodgett (LB) films of (C16H33-TCNQ)(0.4)(C17H35. DMTTF)(0 .6) prepared by the vertical lifting technique have been carried out. [(C16H33-TCNQ)(0.4)(C17H35. DMTTF)(0.6) denotes the surface-active cha rge-transfer complex of hexadecyltetra-cyanoquinodimethane (C16H33. TC NQ) and heptadecyldimethyltetrathiofulvalene (C17H35. DMTTF).] Excess 1/f noise has been observed over the frequency range of 1-10(4) Hz. We found that the noise power is proportional to the square of de curren t flowing through the sample and has a power spectrum varying approxim ately as f(-1) over the frequency range studied. The noise pou er is t hree orders of magnitude larger than that predicted by Hooge's formula . A theoretical model for the origin of 1/f noise due to fluctuations of the number of charge propagation paths in the sample is proposed. T he calculations of 1/f noise level using this model are in quantitativ e agreement with experimental results not only in the LB films but als o in tetrathiofulvalene-tetracyanoquinodimethane (TTF-TCNQ) crystals.