Thermally Oxidized AlxGa2–xO3/n-Al0.6Ga0.4N:Si Unipolar Resistive Random-Access Memory

Thermally oxidized AlxGa2–xO3/n-Al0.6Ga0.4N:Si resistive random access memory (RRAM) presented unipolar resistive switching characteristics. The resistance ratio of the high-resistance state (HRS) to the low-resistance state (LRS) was higher than 104 for the RRAM device. After a retention time of 10000 s, the ratio of HRS/LRS exhibited no obvious degradation. The thickness of the Ti layer on the top electrode affected the switching cycles of the RRAM. The resistive switching cycles increased from 17 to 45 times with increasing Ti thickness from 1 to 5 nm. In addition to the effect of Ti thickness, the oxygen (O2) plasma treatment on the thermally oxidized AlxGa2–xO3 layer improved the resistive switching cycles of the RRAM. The resistive switching cycles increased from 45 to 165 times with increasing the O2 plasma treatment time from 0 to 90 min. Ti formed a TiOx layer, which could act as an oxygen reservoir. Thick Ti and O2 plasma treatment could increase the amount of oxygen in the TiOx layer. Oxygen could be supplied to the conductive filaments for redox reactions, leading to an improvement in the resistive switching cycle of RRAM.