• Current Optics and Photonics
• /
• v.6 no.3
• /
• pp.252-259
• /
• 2022

In this paper, a dual-function dynamically tunable metamaterial absorber is proposed. At frequency points of 1.545 THz and 3.21 THz, two resonance peaks with absorption amplitude of 93.8% (peak I) and 99.4% (peak II) can be achieved. By regulating the conductivity of photosensitive silicon with a pump laser, the resonance frequency of peak I switches to 1.525 THz, and that of peak II switches to 2.79 THz. By adjusting the incident polarization angle by rotating the device, absorption amplitude tuning is obtained. By introducing two degrees of regulation freedom, the absorption amplitude modulation and resonant frequency switching are simultaneously realized. More importantly, dynamic and continuous adjustment of the absorption amplitude is obtained at a fixed resonant frequency, and the modulation depth reaches 100% for both peaks. In addition, the sensing property of the proposed MMA was studied while it was used as a refractive index sensor. Compared with other results reported, our device not only has a dual-function tunable characteristic and the highest modulation depth, but also simultaneously possesses fine sensing performance.

• Journal of Sensor Science and Technology
• /
• v.9 no.3
• /
• pp.242-247
• /
• 2000

$Pb_{0.99}[(Zr_{0.6}Sn_{0.4})_{0.9}Ti_{0.1}]_{0.98}Nb_{0.02}O_3(PNZST)$ thin films were deposited by RF magnetron sputtering on $(La_{0.5}Sr_{0.5})CoO_3(LSCO)/Pt/Ti/SiO_2/Si$ substrate using a PNZST target with excess PbO of 10 mole%. The thin films deposited at substrate temperature of $500^{\circ}C$, and at RF power of 80W were crystallized to a perovskite phase after rapid thermal annealing(RTA). The thin films annealed at $650^{\circ}C$ for 10 seconds in air exhibited the good structures and electrical properties. The fabricated PNZST capacitor had a remanent polarization value of about $20\;{\mu}C/cm^2$ and coercive field of about 50 kV/cm. The reduction of the polarization after $2.2{\times}10^9$ switching cycles was less than 10%.

• Journal of Sensor Science and Technology
• /
• v.11 no.1
• /
• pp.48-53
• /
• 2002

Ferroelectric $Pb_{0.99}[(Zr_{0.6}Sn_{0.4})_{1-x}Ti_x]_{0.98}Nb_{0.02}O_3$(PNZST) thin films were deposited by a RF magnetron sputtering on $(La_{0.5}Sr_{0.5})CoO_3$(LSCO)/Pt/Ti/$SiO_2$/Si substrate using a PNZST target with excess PbO of 10 mole%. The crystallinity and electrical properties of the thin films with various composition ratio were investigated. The thin films deposited at the substrate temperature of $500^{\circ}C$ and the power of 80 W were crystallized to a perovskite phase after rapid thermal annealing(RTA) at $650^{\circ}C$ for 10 seconds in air. A PNZST thin films with Ti of 10 mole% showed the good crystallinity and ferroelectric properties. The remanent polarization and coercive field of the PNZST capacitor were about $20\;{\mu}C/cm^2$ and 50 kV/cm, respectively. The reduction of the polarization after $2.2{\times}10^9$ switching cycles was less than 10%.

• Journal of the Institute of Electronics Engineers of Korea SD
• /
• v.38 no.7
• /
• pp.473-478
• /
• 2001

Ferroelectric P $b_{0.99}$［(Z $r_{0}$ 6S $n_{0.4}$)/0.9/ $Ti_{0.1}$］0.98/N $b_{0.02}$ $O_3$(PNZST) thin films were deposited by a RF magnetron sputtering on L $a_{0.5}$S $r_{0.5}$Co $O_3$(LSCO)/Pt/Ti/ $SiO_2$/Si substrate using a PNZST target with excess PbO of 10 mole%. The crystallinity and electrical properties of the thin films annealed at various temperature and time were investigated. The thin films deposited at the substrate temperature of 500 $^{\circ}C$ and the power of 80 W were crystallized to a perovskite phase after rapid thermal annealing(RTA). The thin films annealed at 650 $^{\circ}C$ for 10 seconds in air exhibited the good crystal structures. The remanent polarization and coercive field of the PNZST capacitor were about 20 $\mu$C/$\textrm{cm}^2$ and 50 kV/cm, respectively. The reduction of the polarization after 2.2$\times$10$^{9}$ switching cycles was less than 10 %..10 %......

• Journal of the Institute of Electronics Engineers of Korea SD
• /
• v.38 no.11
• /
• pp.765-770
• /
• 2001

Metal-ferroelectric-insulator- semiconductor(MFTS) devices by using rapid thermal annealed (RTA) LiNbO$_3$/AIN/Si(100) structures were successfully fabricated and demonstrated nonvolatile memory operations. Metal-insulator-semiconductor(MIS) C-V properties with high dielectric AIN thin films showed no hysteresis and good interface properties. The dielectric constant of the AIN film calculated from the capacitance at the accumulation region in the capacitance-voltage(C-V) characteristics was about 8. The C-V characteristics of MFIS capacitor showed a hysteresis loop due to the ferroelectric nature of the LiNbO$_3$ thin films. Typical dielectric constant value of LiNbO$_3$ film of MFIS device was about 23. The memory window width was about 1.2 V at the gate voltage of $\pm$5 V ranges. Typical gate leakage current density of the MFIS structure was the order of 10$^{-9}$ A/$\textrm{cm}^2$ at the range of within $\pm$500 kV/cm. The ferroelectric capacitors showed no polarization degradation up to about 10$^{11}$ switching cycles when subjected to symmetric bipolar voltage pulse(peak-to-peak 8 V, 50 % duty cycle) in the 500 kHz.

• Journal of the Korean Ceramic Society
• /
• v.54 no.4
• /
• pp.261-271
• /
• 2017

Environment-friendly $(K,Na)NbO_3-based$ (KNN) lead-free piezoelectric materials have been studied extensively in the past decade. Significant progress has been made in this field, manifesting competitive piezoelectric performance with that of lead-based, for specific application scenarios. Further understanding of the relationship between high piezoelectricity and microstructure or more precisely, ferroelectric domain structure, domain wall pinning effect, domain wall conduction and local polarization switching underpins the continuous advancement of piezoelectric properties, with the help of piezoresponse force microscopy (PFM). In this review, we will present the fundamentals of scanning probe microscopy (SPM) and its cardinal derivative in piezoelectric and ferroelectric world, PFM. Some representative operational modes and a variety of recent applications in KNN-based piezoelectric materials are presented. We expect that PFM and its combination with some newly developed technology will continue to provide great insight into piezoelectric materials and structures, and will play a valuable role in promoting the performance to a new level.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
• /
• 2003.07b
• /
• pp.624-627
• /
• 2003

The BLT thin-films were one of the promising ferroelectric materials with a good leakage current and degradation behavior on Pt electrode. The BLT target was sintered at $1100^{\circ}C$ for 4 hours at the air ambient. $Bi_{3.25}La_{0.75}Ti_3O_{12}$ (BLT) thin-film deposited on $Pt/Ti/SIO_2/Si$ wafer by rf magnetron sputtering method. At annealed $700^{\circ}C$, (117) and (006) peaks appeared the high intensity. The hysteresis loop of the BLT thin films showed that the remanent polarization ($2Pr=Pr^+-Pr^-$) was $16uC/cm^2$ and leakage current density was $1.8{\times}10^{-9}A/cm^2$ at 50 kV/cm with coersive electric field when BLT thin-films were annealed at $700^{\circ}C$. Also, the thin film showed fatigue property at least up to $10^{10}$ switching bipolar pulse cycles under 7 V. Therefore, we induce access to optimum fabrication condition of memory device application by rf-magnetron sputtering method in this report.

• Proceedings of the KIEE Conference
• /
• 1998.07d
• /
• pp.1352-1354
• /
• 1998

$LiNbO_3$ transistor showed relatively stable characteristic, low interface trap density, and large remanent polarization. This paper reports ferroelectric $LiNbO_3$ thin films grown directly on p-type Si(100) substrates by 13.56 MHz rf magnetron sputtering system for FRAM applications. To take advantage of low temperature requirement for growing films, we deposited $LiNbO_3$ films lower than $300 ^{\circ}C$. RTA(Rapid Thermal Anneal) treatment was performed for as-deposited films in an oxygen atmosphere at $600^{\circ}C$ for 60 sec. We learned from X-ray diffraction that the RTA annealed films were changed from amorphous to poly-crystalline $LiNbO_3$ which exhibited (012), (015), and (022) orientations. The I-V characteristics of $LiNbO_3$ films before and after anneal treatment showed that RTA improved the leakage current of films. The leakage current density of films decreased from $10^{-5}$ to $10^{-7} A/cm^2$ at room temperature measurement. Breakdown electric field of the films exhibited higher than 500 kV/cm. The C-V curves showed the clockwise hysteresis represents ferroelectric switching characteristics. From C-V curves, we calculated dielectric constant of thin film $LiNbO_3$ as 27.5 which is close to that of bulk value.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
• /
• 2004.07b
• /
• pp.697-700
• /
• 2004

The SBT$(Sr_{0.8}Bi_{2.4}Ta_2O_9)$ thin films for semiconductor device were deposited on Pt-coated $Pt/TiO_2/SiO_2Si$ wafer by RF magnetron sputtering method at $400[^{\circ}C]$ and annealed at the temperature range from $600[^{\circ}C]$ to $850[^{\circ}C]$. The top electrodes(Pt) were deposited on SBT thin film by DC sputtering method. The crystallinity of SBT thin films were increased with increase of annealing temperature in the temperature range of $600[{\circ}C]\sim850[^{\circ}C]$. The annealing temperature properties were to be most excellent in the case of annealed SBT thin film at $750^{\circ}C]$. And, the maximum remanent polarization$(2P_r)$ and the coercive electric field$(E_c)$ at annealing temperature of $750[^{\circ}C]$ obtained about $11.60[{\mu}C/cm^2]$ and 48[kV/cm], respectively. Specially, it was seen that fatigue properties does not change in $10^{10}$ switching cycle.

• Review of Culture and Economy
• /
• v.21 no.2
• /
• pp.53-88
• /
• 2018

Among the cultural industries, the game industry is the most economically valuable industry. It has been about twenty years since the game policy has been implemented and the game laws have been enacted. If the law is a willing expression for the realization of the policy, the orientation of the game policy can be grasped through revision of the game laws. SOUND RECORDS, VIDEO PRODUCTS, AND GAME SOFTWARE ACT, established in 1999, and GAME INDUSTRY PROMOTION ACT, which was enacted in 2006, are regulated by many revisions. In this paper, I try to understand the direction and meaning of Korean game policy(classification, game dysfunction, gambling, industry growth) through the contents of the revision of the game law for 20 years. The game policy shown through the amendment of the game law is intended to protect the game by regulating the game, and to protect the game user by preventing the gambling and preventing the game dysfunction, and to increase autonomy of users and choice of producers by switching to self rating system, and based on this, an environment for continuous industrial growth is created. In the future, game policies should consider cooperation with social areas beyond game-specific areas. On the other hand, it needs to respond to new agendas such as polarization of industrial structure, fair environment, employment environment.