INCIPIENT ANDERSON LOCALIZATION IN THIN PDXC1-X MIXTURE FILMS

We have studied structural as well as electrical properties of thin granular PdxC1-x films (10 ≤ t 70 nm) in the vicinity of the metal-insulator transition (MIT). The films show metallic resistance behaviour with positive temperature coefficients of resistance (TCR) for x > 0.35 and variable range hopping conductivity (VRH) for x < 0.3. Approaching the MIT (xc = 0.3) from the metallic side, one finds corrections to the low temperature resistance, which can be well explained in the framework of weak localization and electron-electron interaction as long as x > 0.34. In the region closer to the MIT (0.3 < x < 0.34) the PdxC1-x films show anomalous resistance behaviour with a negative TCR even at high temperatures. This is attribute to Incipient Anderson Localization due to a diverging localization length ε{lunate} which becomes larger than the inelastic diffusion length Li or the thermal diffusion length Lee. © 1990.