Study On Resistive Properties Of HfO₂ Composite Structure Thin Films Controlled By Light

In recent years,with the rapid development of electronic information technology,the demand for memory with high memory density,low power consumption,high integration and compatible with complementary metal oxide semiconductor（CMOS）technology is becoming more and more urgent.Because of its unique tunneling mechanism and the restriction of Moore’s Law,non-volatile memory such as Flash is facing the problem of technological and physical limits,and will soon be unable to meet the needs of human memory.Therefore,researchers began to develop new memory in the hope of replacing Flash.Resistive Variable Memory（RRAM）,which is compatible with CMOS,has many advantages,such as simple structure,small size and multi-value storage capability.Although some progress and achievements have been made in the research of RRAM,there are still some unsolved problems,such as large operating voltage,poor parameter uniformity and how to improve the storage density.To address these issues,this paper focuses on the resistive layers of binary metal oxides HfO₂ and Zn O to investigate the resistive characteristics of RRAM under photoelectric synergy.The main contents and results of the study are as follows:Cu/HfO₂/Pt RRAM devices were fabricated by magnetron sputtering technology.In this paper,the resistive properties of Cu/HfO₂/Pt RRAM devices were studied in depth in order to achieve better performance.The results show that the device has a relatively stable bipolar resistive property up to 10⁴ s and a switching ratio greater than 10³.The current conduction mechanism of HfO₂ device at low resistance is ohmic conduction and at high resistance is dominated by SCLC mechanism,and the conductive filaments are composed of oxygen vacancies.Due to the low content and random distribution of oxygen defects in HfO₂ thin films,the resistance and uniformity of devices are poor.Cu/HfO₂-Zn O/Pt RRAM devices were fabricated by magnetron sputtering.The effect of double-layer HfO₂-Zn O on the resistive behavior of the devices was discussed.The experimental results show that the HfO₂-Zn O device has lower forming voltage and operating voltage and better uniformity and stability than the single-layer HfO₂ device.The main reason is that Zn O has smaller oxygen vacancy formation energy and can produce more oxygen defects to participate in the resistive behavior of the device under the action of electric field,so that the operating voltage and uniformity of the device are improved.In addition,the existence of the interface between HfO₂ and Zn O inhibits the random distribution of oxygen defects,that is,the random breakage and formation of oxygen vacancy conductive filaments,which is beneficial to improve the uniformity of the deviceFinally,the resistive behavior of Cu/HfO₂/Pt and Cu/HfO₂-Zn O/Pt RRAM devices under255 nm light source was studied.255 nm illumination has little effect on Cu/HfO₂/Pt device.For Cu/HfO₂-Zn O/Pt RRAM device,the operating voltage and stability of the device can not only be improved with the illumination intensity,but also can be realized by adjusting different illumination power to make the device have multiple resistance states.