Investigation of resistive switching in SiO2 layers with Si nanocrystals

MOS structures with two-layer insulator, SiO2/SiOx, are tested for switching between high and low resistance state. Part of the structures were annealed at 1000 °C for 60 min in N2 in order to form silicon nanocrystals (Si NCs) in a SiOx matrix. Cross-sectional transmission electron microscopy revealed that after the high temperature annealing phase separation takes place and nanocrystals with size of ∼ 4-5 nm are formed. Direct current-voltage measurements showed that bipolar switching occurs only in the annealed c-Si/SiO2/SiOx/Al structures and not in the control samples. A model explaining the resistance change by electric field formation of conductive pathway in the SiOx-Si NCs layer at negative gate voltages and current driven destruction of the conductive filament at positive voltages was verified by high frequency capacitance-voltage (C-V) measurements. From the C-V results the dielectric constant of non-annealed SiOx films with x = 1.3 was calculated to be εSiOx = 4.6.