Light sensitive memristors based on GeSixOy films with Ge nanoclusters

Abstract

For the development of information technology, more and more memory arrays are needed. Recently, memristors have been the most promising candidates for the creation of modern universal memory. The possibility of light stimulated resistive switching (RS) is promising for creating optical computers, technical vision and neuron networks. The studied Si_xGe_yO_z solid alloys films (~50-65 nm) were obtained by simultaneous evaporation of GeO₂ and SiO₂ (or SiO) powders in high vacuum (10^-8 Torr) and deposition onto n+-type, p+-type Si(001), and on Al/SiO₂/Si(001) heated up to 100°C. The transparent indium tin oxide (ITO) contacts were used as top electrode. It was found, that as-deposited GeO_x[SiO]_(1-x) films contain amorphous Ge (a-Ge) nanoclusters. The furnace annealing at temperature 500 °C lead to further forming of a-Ge clusters in both types of the films. Reversible (up to several thousand cycles) RS from high resistance state (HRS) to low resistance state (LRS) (memristor effect) were observed for the semiconductor-dielectric-metal structures, namely p+-Si (or n+-Si)/ GeO[SiO₂] (or GeO[SiO]) /ITO structures (MIS structures) in air atmosphere. Both negative and positive photoconductivity was observed in the annealed MIS structure when both negative/positive voltage biases were applied to the top ITO electrode. This is possibly due to light-stimulated recharging of holes from a-Ge nanoclusters, which act as deep traps. The effects of light-induced RS was observed for annealed MIS structures based on GeO[SiO] films with a-Ge nanoclusters. These results are promising for creation of photomemristors and optoelectronic devices combining the properties of a memristor.