Electrical Characterization of Nickel oxide and Nickel Iron Oxide thin films and Resistive Random Access Memory Devices Grown by Radio Frequency Sputtering.*

The market for non-volatile memory is potentially about to hit a brick wall with the flash technology as it might not be scalable beyond the 14nm node. The need for other storage devices is a hot topic in said market, and one possibility is Resistive RAM (RRAM). These devices can store information through a reversible switch from high to low resistance by means of a soft break-down. In this project the use of NiO and Ni_1-xFe_xO also known as Permalloy Oxide (Ni₈₀Fe₂₀O, PyO) in ReRAM devices are being investigated. Device test wafers with different oxygen concentrations, thicknesses, and electrode materials were made by RF magnetron co-sputtering on p- and n-type Si wafers. Each device wafer contains 32 dies and each die 41 devices. The automated Probe system Summit 12000 was used to measure the IV and CV curves, and the impedance spectra at room temperature. Au/NiFeO/n-Si devices show a strong rectifying effect with forward currents up to 1600 times higher than the reverse current. Devices on p-Si show larger currents than similar devices on n-Si. Results will be discussed in terms of band offsets and the electrode’s work functions of the materials involved.