Study On The Characteristics Of Charge Trapping And Storage Based On Ba_0.6Sr_0.4TiO₃ And Zr_0.5Hf_0.5O₂ Thin Films

Charge trapping memory is widely used in laptops,mobile phone and digital cameras and other consumer electronic products,and It is popular in the scientific community due to it‘s low write/erase voltage,high scalability as well as superior resistance of fatigue than conventional polysilicon floating gate memory.In this study,we present a metal/ Ba_0.6Sr_0.4TiO₃/SiO₂/Si（MBOS）single film device structure for charge trapping memory（CTM）,where the single Ba_0.6Sr_0.4TiO₃（BST）film acts as the block oxide layer and charge trapping layer.This MBOS device structure demonstrates excellent charge trapping characteristics,a large memory window up to 8.4V under applied voltages of ±12V,robust charge retention of only 4% charge loss after 1.08×10⁴ seconds,fast switching rate and great program/erase endurance.Property of defect states in the Ba_0.6Sr_0.4TiO₃ film is investigated through measurements of photoluminescence and photoluminescence excita tion spectroscopy.The energy levels of these defect states are found to distribute between 2.66 e V and 4.05 e V above the valence band.The inter-diffusion at the Ba_0.6Sr_0.4TiO₃/SiO₂ interface is observed by high-resolution transmission electron microscopy.More defect sites were created to obtain a better charge trapping capability and retention characteristics.Secondly,graphene which has one atomic thickness will further extend Moore’s advantage.In addition,it also gives the vitality of the microelectronics industry with its excellent performance in optics,thermodynamics,mechanics,electricity and so on.The CTM devices with Pd/Zr_0.5Hf_0.5O₂/GQDs/SiO₂/Si structure and Pd/Zr_0.5Hf_0.5O₂/SiO₂/Si structure of CTM devices were fabricated.The electrical properties of these two kinds of devices were tested and their microstructures were photographed.By comparing the performance of these two kinds of devices,the advantage of application of GQDs in CTM devices is obtained.The first advantage is to reduce the turn-on voltage,and the second advantage is to improve the performance of the device.On the other hand,resistive random access memory with its simple metal-insulator-metal structure,good compatibility with current complementary metal oxide semiconductor technology,low power consumption and good retention characteristics,is widely studied as the next generation nonvolatile memory.On the base of several mechanisms of resistance change based on RRAM,Zr_0.5Hf_0.5O₂（ZHO）can be used as the material of resistance change.Due to the existence of many natural oxygen vacancies,it has become one of the most promising materials in RRAM.In our work,due to the good conductivity of TiN,we fabricated the device of Pt/ZHO/TiN/ZHO/TiN structure and we also tested electrical properties of the device.In the I-V curve,both set and reset phenomena appear in the forward scan voltage and negative scan voltage,which is a typical thresholding phenomenon.The device is scanned by 100 current and voltage cycles,the Vset and Vreset distributions are very concentrated and stable,and the Roff and Ron are different in the two states and the distribution is also stable.