아래와 같이 세미나를 개최하오니 많이 참석해 주시기 바랍니다. 아 래 제목: Resistance Switching Behavior of Epitaxially Grown NiO Thin Films 연사: 이승란 박사(서울대학교 재료공학부) 일시: 2009년 9월 15일(화) 15:00-17:00 장소: 기초과학연구소 세미나실(31317호) 초록: Resistance switching phenomenon in metal-oxide-metal (MOM) structures has attracted great attention due to its potential applications in nonvolatile resistance random access memory (ReRAM) devices. In addition to many efforts to improve device performance, extensive studies have been devoted to explain the switching mechanism. Among various oxide materials, polycrystalline NiO (poly-NiO) films have been intensively studied owing to the better retention and endurance properties of NiO than other oxide systems. In order to understand resistance switching mechanism of NiO, we have deposited epitaxial NiO (epi-NiO) films on SrRuO3 (SRO) bottom electrodes as a model system. Interestingly, in contrast to the previous reports on unipolar switching behavior of poly-NiO, epi-NiO with Pt and CaRuO3 (CRO) as the TEs shows bipolar switching behavior. However, when reactive metals are employed as TEs such as Al and Ti, epi-NiO does not show successive resistance switching, indicating that the TE/epi-NiO interface plays a key role in bipolar resistance switching of epi-NiO. To understand the conduction properties of TE/epi-NiO, we studied the temperature dependence of the I-V characteristics for various TEs and resistance states. The temperature dependence of the pristine TE/epi-NiO suggests that oxygen ions in an epi-NiO surface migrates and oxidizes the TEs except CRO, resulting in an interfacial oxide layer between the TEs and epi-NiO. Furthermore, after the electroforming process, the temperature dependence of the ON and OFF states exhibits metallic and non-insulating behavior, respectively. From our experimental results, we suggest the interfacial oxide is responsible for the insulating behavior of the pristine state and the role of the electroforming process is to make conducting path in the interfacial oxide to epi-NiO. The details of the switching mechanism of epi-NiO will be discussed further. 22906087062290608706