Degradation analysis and characterization of multifilamentary conduction patterns in high-field stressed atomic-layer-deposited TiO2/Al2O3 nanolaminates on GaAs

In this paper, the effects of applying a high-field electrical stress on TiO2/Al2O3 nanolaminates grown by atomic layer deposition onto a p-type GaAs substrate are investigated. First, it is shown that the current-time (I-t) characteristic of the devices during a constant voltage stress follows the extended Curie-von Schweidler law for dielectric degradation. The application of voltage sweeps from negative to positive bias and back also reveals an hysteretic behavior of the current-voltage (I-V) characteristic typical of the resistive switching mechanism ocurring in these and others high permittivity oxide films. Second, we show that after the detection of the breakdown event the capacitors exhibit a random spot pattern on the top metal electrode (Al) associated with the generation of multifilamentary conduction paths running across the insulating film. The number of generated spots depends on the magnitude of the electrical stress and for a sufficiently large density, it is possible to demonstrate that they are spatially uncorrelated. The analysis is carried out using spatial statistics techniques such as the intensity plot, the interspot distance histogram, and the pair correlation function.