Conduction and stability of holmium titanium oxide thin films grown by atomic layer deposition

Holmium titanium oxide (HoTiOx) thin films of variable chemical composition grown by atomic layer deposition are studied in order to assess their suitability as dielectric materials in metal-insulator-metal electronic devices. The correlation between thermal and electrical stabilities as well as the potential usefulness of HoTiOx as a resistive switching oxide are also explored. It is shown that the layer thickness and the relative holmium content play important roles in the switching behavior of the devices. Cycled current-voltage measurements showed that the resistive switching is bipolar with a resistance window of up to five orders of magnitude. In addition, it is demonstrated that the post-breakdown current-voltage characteristics in HoTiOx are well described by a power-law model in a wide voltage and current range which extends from the soft to the hard breakdown regimes.