||Recently, with the advancement of portable electronic products, nonvolatile memories have attracted much attention. In order to increase the capacity and density of nonvolatile memory, the device must be continuously miniaturized. However, with their scaling-down, conventional nonvolatile floating gate memory has reached it physical limits. Hence, the new generations of nonvolatile memories are developed to solve this problem. Resistive random access memory (RRAM) is considered to replace conventional flash memory become a great potential candidates for nest generation nonvolatile memories due to its advantageous properties of simple structure and excellent operation property. We will investigate the resistive switching mechanisms of the InxGayO1-x-y based RRAM and amorphous indium-gallium-zine- oxide thin film transistors (a-IGZO TFTs).|
In the first part, we investigated the gallium oxide based RRAM with different oxygen concentrations since the resistance switching characteristics is related to oxygen ions migration. Moreover, the different resistance switching property is observed and the effective thickness can be estimated. In the second part, we proposed indium oxide based RRAM devices and investigate the different resistance switching behavior between transient mode and steady mode due to the cross-section area of the conduction path. The indium oxide based RRAM device exhibit a self-compliance behavior in the material itself due to the variable series resistor. Moreover, we investigated indium oxide with oxygen concentrations since the resistivity and electrical property of indium film related to oxygen concentration. The lower self-compliance current can be attributed to larger variable series resistor and the operation current can be reduced effectively from the additional oxygen ions.
In the third part, we design the indium gallium oxide based RRAM and observed the two kinds of resistance switching behavior by different operation conditions. The different resistance switching mechanism proportions are demonstrated the oxygen vacancies and metallic filaments by electric property and material analysis. Finally, the a-IGZO TFTs can be operated either as transistors or RRAM device. These resistance switching characteristics are dominated by oxygen vacancies and the formation of an oxygen-rich layer.