Resistive switching properties and transport mechanism using Cr/BaTiO3/TiN structure

• Main Authors: Zong Yi Wu, 吳宗益
• Other Authors: S. Maikap
• Format: Others
• Language: en_US
• Published: 2016
• Online Access: http://ndltd.ncl.edu.tw/handle/24edt7

碩士 === 長庚大學 === 電子工程學系 === 104 === Bipolar resistive switching characteristics of the 5 nm-thick and 2.5 nm-thick BaTiO3 films using a Cr/BaTiO3/TiN structure have been reported for the first time. The leakage current increases as well as formation voltage decreases with increasing device size from 0.4×0.4 to 4×4 µm2. Current transport mechanism of these devices has been analyzed. Oxygen ions migration under external bias leads to the switching mechanism. Hopping distance and Fowler-Nordheim tunneling are observed at higher bias regions or high field. The resistance ratio is increased up to 2000 and it increases with increasing current compliance. Both devices have shown gradual dissolution characteristics by modulating negative bias after SET the devices and illustrated a schematic model. Excellent tunable multi-states are observed by varying negative stop voltage. The multilevel retention in LRS and four HRS states are obtained. Both devices have shown robust read endurance of 106 cycles. The 5 nm-thick BaTiO3 film shows three hours of robust retention with resistance ratio of 2000 in room temperature, even the 2.5 nm-thick device shows data retention at 85̇oC. Thicker film shows higher resistance ratio and thinner film shows repeatable switching cycles, which leads to longer dissolution gap in thicker film and higher defects in thinner film. Hence, these excellent multistate bipolar resistance characteristics of our devices imply the promising application in multistate non-volatile memories in near future.