| Summary: | 碩士 === 國立清華大學 === 工程與系統科學系 === 99 === The objective of this study is to improve the resistive switching characteristics of ZrO2 RRAM by doping nitrogen into ZrO2 insulator layer. The N-doped ZrO2 thin films were deposited by magnetron sputtering with nitrogen content ranging from 1.8% to 6.0%. The I-V characteristics of the Pt/N-doped ZrO2/TiN devices were analyzed at room temperature. Film thickness and microstructure were observed using a field-emission scanning electron microscope. The crystal structure was characterized by glancing incidence X-ray diffraction. Bipolar resistive switching was observed in the Pt/N-doped ZrO2/TiN devices. The Pt/N-doped ZrO2/TiN memory devices effectively increased resistance ratios with increasing the ON state current and slightly lowering the OFF state current. The introducing of nitrogen also facilitated the lowering of the operation voltage of SET process, but did not change the operation voltage of RESET process which mainly due to Joule-Heating effect. Since the doping of nitrogen led to the replacement of O2- by N3- in the ZrO2 lattice, more oxygen vacancies were created to fulfill the charge neutrality requirement. Thus, a more conductive and easier to switch oxygen vacancy filaments can be produced. Moreover, we also discovered that N-doped c-ZrO2 has larger leakage current at OFF state than m-ZrO2, which led to a smaller resistance ratio.
|
|---|
