Study On γ Ray,Proton,and Heavy Ion Irradiation Damage Of TiO₂ Resistance Random Access Memory

The binary metal oxide based resistive switching memory have been identified as a prospective candidate for next generation nonvolatile memories due to their advantages,such as simple sandwich structure of"upper electrode/resistive layer/bottom electrode",high storage density,high read-write speed,low power consumption and radiation resistance.The resistive switching comes from the connecting/disconnecting the upper and bottom electrodes through conductive filaments composed of oxygen defects in the binary metal oxide based resistive layer.However,the oxygen defects induced by the irradiation can move under electric field,which leads to the redistribution of oxygen defects and then affect the performance such as high/low resistance states and operating voltage.In this paper,the damage law and mechanism of TiO₂-based resistive switching memory after irradiation of⁶⁰Coγray,protons and heavy ions were studied,and its I-V model of irradiation was established.The main research contents and results are as follows:1.The effect of ⁶⁰Coγray irradiation on the Pt/TiO₂ nanorod/Ti resistive switching memory was studied.The results show that with the increase of the total dose from 0 to 1Mrad（Si）,the device’s SET voltage and low resistance state have almost no change,RESET voltage,high resistance state and the ON/OFF ratio are decreased.After 1 Mrad（Si）irradiation,the ON/OFF ratio of the device can still approaching 10².The XPS test and GEANT4 simulation results show that the increase of oxygen defects in the resistive layer is induced by ⁶⁰Coγray irradiation,which is the main reason for the decrease of RESET voltage and high resistance state.On this basis,the I-V model of TiO₂ nanorod based resistive switching memory after ⁶⁰Coγray irradiation is built based on the Voltage Thr Eshold Adaptive Memristor model.The I-V curve at different doses of irradiation is simulated,which is in good agreement with the experimental results.2.The effect of proton irradiation on the Au/TiO₂ film/Ti resistive switching memory was studied.The results show that with the increase of the fluence from 0 to 1×10¹¹ cm^-2,the device’s low resistance state have almost no change,the RESET voltage is slightly reduced,high resistance state,the SET voltage and the ON/OFF ratio are decreased.After 1×10¹¹ cm^-2irradiation,the ON/OFF ratio of the device can still approaching 10².The XPS test and SRIM simulation results show that the increase of oxygen defects in the resistive layer is induced by proton irradiation,which is the main reason for the decrease of SET voltage and high resistance state.On this basis,the I-V model of TiO₂ flim based resistive switching memory after proton irradiation is based on the VTEAM model.The I-V curve at different fluence of irradiation is simulated,which is in good agreement with the experimental results.3.The ⁵⁶Fe heavy ion irradiation on the TiO₂ based resistive switching memory is studed used SRIM.The simulation results show that ⁵⁶Fe ion irradiation effect on TiO₂ is mainly total ionizing dose effect.However,the non-ionizing energy of ⁵⁶Fe ion in the TiO₂ accounts for about 15%,the generated oxygen vacancy which will damage the TiO₂ based resistive switching memory.Based on the ⁶⁰Coγray and proton irradiation experiments,the relationship between the increase in oxygen vacancies after irradiation and parameters of device was established.Predict the I-V curves of Pt/TiO₂ NRAs/Ti and Au/TiO₂ film/Ti resistive switching memory under different doses of heavy ion irradiation.