Study Of Resistive Switching Characteristics Induced By Lateral Conductive Bridges
This paper investigates resistive switching characteristics of a resistive random-access memory (RRAM) with a lateral device structure. The resistive switching layer is an oxide semiconductor AlZnSnO (AZTO), which was prepared using a solution process. A ZnO solution was obtained by mixing anhydrous ethanol and zinc acetate dehydrate [Zn(CH3COO)2‧2H2O]. A precursor of chloride dehydrate [SnCl2‧2H2O] was used to prepare a SnO solution while aluminum nitrate nonahydrate [Al(NO3)3] was used to obtain an AlOx solution. The solutions were individually stirredat 60 oC for one hour. The AlZnSnO solution was yielded by mixing the above solutions with mono-ethanolamine (MEA) followed by stirring at 70 oC for 30 min. The AZTO solution was aged at room temperature for 24 hours. A n+ Si wafer cleaned by diluted HF solution and deionized water was used as the substrate. The AZTO resistive switchinglayer was deposited on the substrate using a spin coating process at 3000 rpm for 20 s. Then, the sample was cured at 120 °C for 10 min to remove the solvent and organic residues. The spin coating process was repeated for three times to increase the thickness of the AZTO layer. Indium electrodes were fabricated by pressing indium spheres onto the AZTO surface. Ag electrodes were fabricated using an evaporator. Current-voltage characteristics of three lateral devices of Ag-AZTO-Ag, In-AZTO-In, and Ag-AZTO-In were measured with voltage loops of 0 V-Vmax0 VVmax0 V. The Ag-AZTO-Agdevice shows high conduction currents without resistive switching behavior. Resistive switching characteristics can be observed inthe In-AZTO-In device. However, the resistive window, the resistance ratio of the high resistance state to the low resistance state, is not obvious. For the In-AZTO-Ag device, significant resistive switching characteristics are observed. In addition, the endurance test shows that the resistive switching can reproduce for over 1000 times. The resistive switching behavior can be explained by Ag ion migration andformation/rupture of conductive oxygen-vacancy filaments. The physical mechanism for the resistive switching behavior is investigated, and the carrier conduction mechanism in the AZTO active layer was also explored. This work is helpful for further understanding the influences of the electrodes on the resistive switching characteristics of the lateral AZTO RRAM devices, and is also helpful for the development of future 3-D RRAM technology.
Keywords - Oxide Semiconductor, Current-Voltage Characteristics, Memory Device, solution process.