| Nonvolatile memory has been widely used in many fields, such as aviation/spaceflight, military/national defense, new energy and scientific research. The traditional floating gate memory (Flash memory) is close to its physical limit,its performances of storage and anti-radiation are also more and more difficult to meet the needs of information storage and data processing for aerospace applications.Resistive random access memory (RRAM) is one of the most promising next-generation nonvolatile memories, and it has better performances than flash memory in many aspects such as device structure, operation speed, scalability and three-dimensional integration.However, RRAM is still in the laboratory research ofchip development, and the research on the radiation effects of RRAM is just getting started. In this thesis, a new devicefor RRAM was designed, in which amorphous rare earth doped perovskite oxide was used as the resistive material and the metal conductive filaments was designed to realise a resistive switching.Then the total ionizing dose(TID) effects of 60 Coy-rays on the device were investigated. The main contents and results are as follows:(1) The Bi4Ti3012 (BIT) films were prepared by chemical solution deposition method,and the influences of annealing temperature, film thickness, element doping and post-annealing of electrode on the leakage current characteristics ofthe prepared films were investigated. With the increase of annealing temperature, the crystallinity and surface roughness increase, and the leakage currentincreases exponentially. By increasing the film thickness and elements doping,the leakage current of BIT films could be slightly decreased.And through appropriate post-annealing treatment of the Pt electrode, the leakage current is significantly reduced through appropriate post-annealing treatment of the Pt electrode.(2) The BIT-based resistive devices were fabricated, and the influencesof crystallinity, Nd doping, and electrode activity on resistive switching characteristics of BIT-based devices were investigated. Result shows thatit's harder to switching the original resistance stateofthe amorphous BIT based devices than ofthe crystallized BIT baseddevices.A more stable high resistance stateis obtained in the Nd doped-BIT (a-BNT)based device than the undoped-BIT based device, and a larger forming voltage is needed usually which is about 15 V. The devices with an active metal Ag top-electrode,i.e.Ag/a-BNT/Pt, havemore stable resistive switchingcharacteristics than the device with a inertia Pt top-metal (Pt/a-BNT/Pt), and these devices have a good cycling performance,low operating voltage (<3 V), low operating current (< 10 mA),largeon/off current ratio (>104),well retention performance (>104 s).(3) TheTID effects of60Coy-rays on the Ag/a-BNT/Ptdevices wereinvestigated.After different TIDs up to 200 krad(Si), 500 krad(Si) and 1 Mrad(Si), the resistances of the device didn't change much.With the increase of TID, the operating voltageslightly increases. After the TID of 1 Mrad(Si), the Ag/a-BNT/Pt devices works well,and the high and low resistance stablely maintainsduring the retention test of 5×104 s.These results show that the Ag/a-BNT/Ptdevices have a good immunity to ionizing radiation, which is mainly due to its uniform amorphous nature ofa-BNT without crystal boundaries and metal conductive filaments in low resistance state. |
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