Current noise in thin film Al/Al 2O 3/Au sandwiches

Abstract

Information is presented about the mode of electrical conductance in a Me/MeO/Me sandwich, a type of structure that has been subject to extensive earlier investigations. The dynamics of the electrical current fluctuations were determined for the Al/Al 2O 3/Au sandwich. Sandwiches with a 17 nm thick alumina interlayer were measured under vacuum conditions at room and 100 K temperatures. I–V characteristics of leakage current were found not symmetric and contain linear parts in In (I) ∼ V 1 2 plot. Power spectra of leakage current noise show relaxation processes at low frequencies which depend on applied voltage and temperature. Amplitude distribution of the leakage current fluctuations is Gaussian at low voltages but at higher voltages (6 V) contains local maxima. The appearance of the multilevel fluctuations corresponds to the voltage region when sandwich structures begin to be unstable and shows qualitative changes in a conduction mechanism. The state indicated by increasing noise power can result in irreversible structural changes—electroformation—when critical conditions are reached. The noise spectra measured at the two different temperatures show an important role of heat dissipation in the structure.