Resistance Switching Properties Of Amorphous Carbon And Gadolinium Oxide Films

Resistive random access memory?RRAM?based on resistive switching?RS?effect has attracted considerable interest for the next generation nonvalatile memory devices,owing to its advantages of simple structure,low power consumption,fast operating speed and high density.The amorphous carbon?a-C?film has simple composition,stable structure and low cost,making it an ideal candidate for RRAM devices.The materials of gadolinium oxide?Gd₂O₃?have become a research hotspot because of its high resistivity,high dielectric constant and large band gap.In this work,the a-C and Gd₂O₃ films are used as dielectric layer,their RS behavior are studied systematically,and underlying mechanism of those properties are discussed finally.?1?The a-C film is deposited by Pulsed laser deposition?PLD?at room temperature.The Ag electrodes are prepared by vacuum evaporation and magnetron sputtering.It is found that the Ag/a-C/Pt device obtained by the magnetron sputtering has better resistance switching properties than prepared by the vacuum evaporation.Then the RRAM devices with different powers are prepared by magnetron sputtering.All the devices have realized a bipolar switching when the power is between 9.2W and14.4 W.The best resistive switching characteristic is obtained when the power is 9.2W with a repeated measurement up to 20 cycles.The values of Set and Reset voltages are only 0.2V in this device.We suggest that the formation and rupture of the Ag conductive filament?CF?is responsible for the RS effect in these Ag/a-C/Pt devices.When the power is between 16.2W and 22.5W,the initial state is in a low-resistance state and the I-V curve become reverse 8.We propose that the Ag CF may has been formed during the preparation of the Ag topelectrode due to the large sputtering power.All the devices prepared under this power range has no forming process,highlighting the advantages of low energy consumption.When the power is equal to 22.5W,the device shows no resistive switching effect.It is likely that there is too much Ag in the film due to the largest sputtering power in this device.?2?A series of Gd₂O₃ films with different temperatures are prepared using the PLD technique.The Gd₂O₃ film is amorphous when growing at 300°C and is crystallized at 500°C or 700°C.The Ti/Gd₂O₃/Pt and Ag/Gd₂O₃/Pt are deposited at three substrate temperatures?300°C,500°C and 700°C?.The measurements show that the Ag/Gd₂O₃/Pt devices prepared under three substrate temperatures demonstrate stable bipolar resistance switching characteristic and good retention.And the Ag/Gd₂O₃/Pt device prepared at 300°C shows good reproducibility,large resistance ratio,low power consumption.