Reliability study of organic nonvolatile resistive memory at elevated temperatures

학위논문 (석사)-- 서울대학교 대학원 : 물리·천문학부, 2016. 2. 이탁희.In this study, nonvolatile organic memory devices were fabricated by using PI:PCBM (polyimide (PI) and 6-phenyl-C61 butyric acid methyl ester (PCBM) as an active memory material with Al/PI:CPBM/Al structure. As changing temperature from room temperature to 470 K, PI:PCBM organic memory devices showed good nonvolatile memory properties in terms of distribution of ON state current and OFF state current, threshold voltage of OFF state to ON state transition, retention, and endurance. These organic memory devices exhibited excellent ON/OFF ratio (ION/IOFF >103) through more than 200 times ON/Off switching cycles, and maintained ON/OFF states for longer than 104 seconds without showing any serious degradation under the measurement temperature up to 470 K. The structural robustness against thermal stress was confirmed through TEM cross-sectional image and AFM image of active layer after retention test at 470 K during 10,000 seconds. This study demonstrated that the operation of organic memory devices under high temperatures was able to be controlled by the parameters which was already used for room temperature, and that the structure of organic memory devices was maintained during thermal stress. These results may make it possible the utility of nonvolatile organic memory devices for high temperature environments.Chapter 1. Introduction 1 1.1. Achievements of organic memory 1 1.2. Operation under thermal stress 2 Chapter 2. Experiments 3 2.1. Memory material preperation 3 2.2. Fabrication 4 2.3. Devices charaterization and measurement 6 Chapter 3. Results and Discussions 7 3.1. Operation Characteristics 7 3.1.1. Current voltage curves 7 3.1.2. ON/OFF current ratios 9 3.1.3. Conduction mechanism 10 3.2. Statistical data under temperature variation 12 3.2.1. ON current and OFF current statistics 12 3.2.2. Threshold voltage statictics 13 3.3. Thermal robustness 16 3.3.1. Electric operation robustness 16 3.3.2. Structural robustness 18 Chapter 4. Conclusions 21 Appendix 22 References 24 국문초록(Abstract in Korean) 27Maste