Improved resistive switching characteristics of a Pt/HfO₂/Pt resistor by controlling anode interface with forming and switching polarity

Jung, Yong Chan,Seong, Sejong,Lee, Taehoon,Kim, Seon Yong,Park, In-Sung,Ahn, Jinho Elsevier BV * North-Holland 2018 Applied Surface Science Vol.435 No.-

<P><B>Abstract</B></P> <P>The anode interface effects on the resistive switching characteristics of Pt/HfO<SUB>2</SUB>/Pt resistors are investigated by changing the forming and switching polarity. Resistive switching properties are evaluated and compared with the polarity operation procedures, such as the reset voltage (V<SUB>r</SUB>), set voltage (V<SUB>s</SUB>), and current levels at low and high resistance states. When the same forming and switching voltage polarity are applied to the resistor, their switching parameters are widely distributed. However, the opposite forming and switching voltage polarity procedures enhance the uniformity of the switching parameters. In particular, the V<SUB>s</SUB> distribution is strongly affected by the voltage polarity variation. A model is proposed based on cone-shaped filament formation through the insulator and the cone diameter at the anode interface to explain the improved resistive switching characteristics under opposite polarity operation. The filament cone is thinner near the anode interface during the forming process; hence, the anode is altered by the application of a switching voltage with opposite polarity to the forming voltage polarity and the converted anode interface becomes the thicker part of the cone. The more uniform and stable switching behavior is attributed to control over the formation and rupture of the cone-shaped filaments at their thicker parts.</P> <P><B>Highlights</B></P> <P> <UL> <LI> The anode interface effect on resistive switching properties is investigated. </LI> <LI> The opposite polarity operation for improving switching uniformity is proposed. </LI> <LI> The stable resistive switching operation occurs at thick part of conical filament. </LI> </UL> </P>

Size effect on polarization switching kinetics of P(VDF-TrFE) copolymer nanodots

Ahn, Yoonho,Son, Jong Yeog ELSEVIER 2017 ORGANIC ELECTRONICS Vol.41 No.-

<P><B>Abstract</B></P> <P>We demonstrate polarization switching kinetics of poly(vinylidene fluoride-<I>ran</I>-trifluoroethylene) P(VDF-TrFE) nanodots depending on their sizes. Ferroelectric copolymer P(VDF-TrFE) nanodots, ranging from 20 to 250 nm in lateral size, were deposited on a Nb-doped SrTiO<SUB>3</SUB> substrate by a position-controlled dip-pen nanolithography technique. Ferroelectric switching characteristics of P(VDF-TrFE) nanodots was investigated by piezoresponse force microscopy. Asymmetric switching behavior was observed during switching process, indicating that the threshold electric fields for polarization reversal were measured differently under the same conditions according to the switching polarity. Significantly, when the size of P(VDF-TrFE) nanodot approached around 250 nm, electric fields for polarization switching were compatible with those of the P(VDF-TrFE) thin film. We suggest that the electric fields required for polarization reversal of the P(VDF-TrFE) nanodots present asymmetric switching behaviors, and asymptotic behavior be observed as the nanodots increase in lateral size.</P> <P><B>Highlights</B></P> <P> <UL> <LI> P(VDF-TrFE) nanodots were fabricated by dip-pen nanolithography. </LI> <LI> Ferroelectric switching kinetics of the P(VDF-TrFE) nanodots was investigated. </LI> <LI> Asymmetric switching behavior was observed depending on their switching polarity. </LI> <LI> Size effect was shown on switching electric field of the P(VDF-TrFE) nanodots. </LI> </UL> </P> <P><B>Graphical abstract</B></P> <P>[DISPLAY OMISSION]</P>

Direct Observation of Heterogeneous Nucleation for Polarization Switching in (001)-oriented Pb(Mg1/3Nb2/3)O3-x%PbTiO3 Crystals by Piezo-force Microscopy

( Eun Gu Lee ) 조선대학교 공학기술연구원 2008 공학기술논문지 Vol.1 No.2

Polarization switching in (001)-oriented Pb(Mg1/3Nb2/3)O3-x%PbTiO3 (PMN-x%PT) crystals for x = 20 and 35at% has been investigated by scanning force microscopy in a piezoresponse mode under applying a DC electrical voltage (Vdc). The results demonstrate that switching initiates by the nucleation of nano-sized polar regions with a reversed polarization. For x = 20, nucleation occurs heterogeneously throughout the volume of the crystal. However, for x = 35, nucleation tends to preferentially initiate near pre-existing twin boundaries; with increasing Vdc, the domains becoming increasingly “diffuse” due to heterogeneous nucleation and growth throughout the crystal.

실리콘 RF MEMS SPDT 스위치를 이용한 패키지 형태의 편파 스위칭 안테나

현익재(Ik-Jae Hyeon),정진우(Jinwoo Chung),임성준(Sungjoon Lim),김종만(Jong-Man Kim),백창욱(Chang-Wook Baek) 대한전기학회 2009 대한전기학회 학술대회 논문집 Vol.2009 No.7

This paper presents a polarization switching antenna integrated with silicon RF MEMS SPDT switches in the form of a package. A low-loss quartz substrate made of SoQ (silicon-on-quartz) bonding is used as a dielectric material of the patch antenna, as well as a packaging lid substrate of RF MEMS switches. The packaging/antenna substrate is bonded with the bottom substrate including feeding lines and RF MEMS switches by BCB adhesive bonding, and RF energy is transmitted from signal lines to antenna by slot coupling. Through this approach, fabrication complexity and degradation of RF performances of the antenna due to the parasitic effects, which are all caused from the packaging methods, can be reduced. This structure is expected to be used as a platform for reconfigurable antennas with RF MEMS tunable components. A linear polarization switching antenna operating at 19 ㎓ is manufactured based on the proposed method, and the fabrication process is carefully described. The s-parameters of the fabricated antenna at each state are measured to evaluate the antenna performance.

Distinct ferroelectric domain switching dynamics in epitaxial BiFeO3 (001) capacitors depending on the bias polarity

임소연,박민선,위상원,정진석,양상모 한국물리학회 2020 Current Applied Physics Vol.20 No.10

Understanding ferroelectric domain switching dynamics at the nanoscale is a great of importance in the viewpoints of fundamental physics and technological applications. Here, we investigated the intriguing polaritydependent switching dynamics of ferroelectric domains in epitaxial BiFeO3 (001) capacitors using transient switching current measurement and piezoresponse force microscopy. We observed the distinct behavior of nucleation and domain wall motion depending on the polarity of external electric bias. When applying the negative bias to the top electrode, the sideways domain wall motion initiated by only few nuclei was dominant to polarization switching. However, when applying the positive bias, most of domains started to grow from the preexisted pinned domains and their growth velocity was much smaller. We suggest that the observed two distinct domain switching behavior is ascribed to the interfacial defect layer.

Direct observation of asymmetric domain wall motion in a ferroelectric capacitor

Lee, J.K.,Shin, G.Y.,Song, K.,Choi, W.S.,Shin, Y.A.,Park, S.Y.,Britson, J.,Cao, Y.,Chen, L.Q.,Lee, H.N.,Oh, S.H. Elsevier Science 2013 ACTA MATERIALIA Vol.61 No.18

We report in situ transmission electron microscopy observations of the 180<SUP>o</SUP> polarization switching process of a PbZr<SUB>0.2</SUB>Ti<SUB>0.8</SUB>O<SUB>3</SUB> (PZT) capacitor. The preferential, but asymmetric, nucleation and forward growth of switched c-domains were observed at the PZT/electrode interfaces, arising due to the built-in electric field induced at each interface. The subsequent sideways growth of the switched domains was inhibited by the depolarization field due to the imperfect charge compensation at the counter-electrode and also at the boundaries with preexisting a-domains, which contributed further to the asymmetric switching behavior. It was found that the preexisting a-domains split into fine a- and c-domains constituting a 90<SUP>o</SUP> stripe domain pattern during the 180<SUP>o</SUP> polarization switching process, revealing that these domains also actively participated in the out-of-plane polarization switching. The real-time observations uncovered the origin of the switching asymmetry and further clarified the importance of charged domain walls and the interfaces with electrodes in the ferroelectric switching processes.

Reliable quantification of trace diarrhetic shellfish poisoning toxins in high-lipid bivalves by UHPLC-ESI-MS/MS in time segment polarity switching mode: Comparison of three extraction methods

Lee, Myoung Eun,Ko, Keon-hee,Park, Na-Hyun,Lee, Wonwoong,Yoo, Hye Hyun,Lee, Jeongmi,Choi, Yong Seok,Hong, Jongki Elsevier 2018 Microchemical Journal Vol.143 No.-

<P><B>Abstract</B></P> <P>Analysis of marine biotoxins in high-lipid bivalves has several limitations due to the coexistence of lipid matrices, low biotoxin concentrations, and the different physiochemical properties of the various biotoxins. In this study, a sensitive and reliable method to simultaneously determine six diarrhetic shellfish poisoning (DSP) toxins (five acidic and one neutral biotoxins) in oysters and mussels was developed based on UHPLC-MS/MS-multiple ion reaction monitoring (MRM) using time segment polarity switching. For effective sample pretreatment, three protocols including syringe filtration, Strata™-X solid phase extraction (SPE), and freezing lipid filtration combined with SPE (FLF + SPE) were evaluated, and FLF + SPE method was shown to be the most effective with high lipid removal efficiency. Aging effects of the UHPLC mobile phase on MS detection sensitivity and retention time shift of DSP toxins were carefully examined. The developed method provided good recoveries ranging from 81.0 to 119.6%, showing no significant matrix effect and assay was linear with coefficients of determination above R<SUP>2</SUP> > 0.99 for all analytes. Validation tests using a certified reference material (CRM) and spiking DSP toxins (OA and DTX-1 at 1.07 μg/g, and DTX-2 at 0.86 μg/g) showed this method to be acceptable, with a relative standard deviation of <0.17% and recovery ranging from 87.29 to 109.97%. Finally, the established method was successfully applied to quantify DSP toxins in 40 oyster and mussel samples collected from Korean fishery markets, ensuring sea food safety.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Three extraction protocols were examined for determining lipophilic DSP toxins in high-lipid bivalves </LI> <LI> SPE combined with FLF was shown the best analytical performance in terms of cleanup efficiency, matrix effect, and sensitivity of DSP toxins. </LI> <LI> Simultaneously determined different polarity DSP toxins in a single run using time segment polarity switching mode </LI> <LI> Validated quantification of trace DSP toxins through CRM analysis and spiking experiments </LI> <LI> Successful monitoring the levels of DSP toxins in high-lipid bivalves </LI> </UL> </P>

Switched-Capacitor Bidirectional Three-Port DC-DC Converter with High Voltage Conversion Ratio

Zahra Saadatizadeh,Pedram Chavoshipour Heris,H. Alan Mantooth 전력전자학회 2023 ICPE(ISPE)논문집 Vol.2023 No.-

In this paper, a three-port high voltage conversion ratio bidirectional DC-DC converter with low voltage and current stresses on switches is proposed. The proposed converter has the capability of having both positive and negative voltage conversion ratios. The proposed converter is expanded in a way that the maximum achievable voltage gain is obtained. As a result, the proposed converter is designed for different voltage gain requirements that has the highest ratio of voltage gain versus total components number. The overall voltage conversion ratios of dc ports are calculated based on the switches number in series and in parallel. In the proposed expandable structure, by using the more switched-capacitor (SC) cells, the voltage gains are increased and the voltage stress on switches is decreased. To verify the analytical results, the experimental results are extracted for 50V/250V/330V voltage.

Polarization-Independent Multiwavelength-Switchable Filter Based on Polarization Beam Splitter and Fiber Coupler

Lee, Yong-Wook The Korean Institute of Electrical Engineers 2009 Journal of Electrical Engineering & Technology Vol.4 No.3

A polarization-independent multiwavelength-switchable fiber filter is proposed based on a polarization beam splitter and fiber coupler, which can function as a polarization-independent transmission or reflection-type interleaving filter. The proposed filter consists of a polarization beam splitter and a Sagnac birefringence loop composed of a 50:50 coupler, high birefringent fibers, and two quarter-wave plates. In the proposed filter, a transmission-type interleaver with a channel isolation > 18 dB or a reflection-type one with a channel isolation of ${\sim}3$ dB, whose channel spacing and switching displacement were 0.8 and 0.4 nm in common, respectively, could be obtained. A channel interleaving operation could be performed by the proper control of waveplates within the Sagnac birefringence loop.

Polarization-Independent Multiwavelength-Switchable Filter Based on Polarization Beam Splitter and Fiber Coupler

이용욱 대한전기학회 2009 Journal of Electrical Engineering & Technology Vol.4 No.3

A polarization-independent multiwavelength-switchable fiber filter is proposed based on a polarization beam splitter and fiber coupler, which can function as a polarization-independent transmission or reflection-type interleaving filter. The proposed filter consists of a polarization beam splitter and a Sagnac birefringence loop composed of a 50:50 coupler, high birefringent fibers, and two quarter-wave plates. In the proposed filter, a transmission-type interleaver with a channel isolation > 18 dB or a reflection-type one with a channel isolation of ~3 dB, whose channel spacing and switching dis-placement were 0.8 and 0.4 nm in common, respectively, could be obtained. A channel interleaving op-eration could be performed by the proper control of waveplates within the Sagnac birefringence loop.