Etching characteristics and surface modification of InGaSnO thin films under Cl_(2)/Ar plasma

Indium gallium tin oxide(IGTO)thin films have the potential for high mobility and lowtemperature processing,which makes them suitable for applications such as display backplanes and high-voltage switching devices.However,very few studies have investigated the plasmaetching characteristics of IGTO and changes in its properties after etching.In this study,the etching characteristics of IGTO were investigated using Cl_(2)/Ar plasma,and changes in surface properties were analyzed.Results showed that the etch rate increased with an increase in the proportion of Cl_(2),with the highest etch rate observed at 69 nm min^(-1)in pure Cl_(2)plasma with a gas flow rate of 100 sccm.Furthermore,increased radio-frequency power caused a rise in the etch rate,while a process pressure of 15 m Torr was optimal.The primary etching mechanism for IGTO thin films under Cl_(2)plasma was a chemical reaction,and an increased work function indicated the occurrence of defects on the surface.In addition,the etching process reduced the surface roughness of Cl_(2)-containing plasma,whereas the etching process in pure Ar plasma increased surface roughness.This study contributes to a better understanding of the plasmaetching characteristics of IGTO and changes in its properties after etching,providing valuable insights for IGTO-based applications.

Improved Cycle Properties of FeS_2 Cathode Material with Metallic Additives

Iron disulfide(FeS_2)cathode active material was prepared from iron and sulfur at room temperature by high energy mechanical alloying.Modified FeS_2 composites containing Co or Ni transition metal powders as additives were also prepared by the same method.Lithium cells with these FeS_2 cathodes were studied for charge-discharge properties at room temperature using 0.5M LiTFSI in tetra(ethylene glycol)dimethyl ether(TEGDME)solvent.Cyclic voltammetry showed two anodic oxidation peaks at 1.8 and 2.5V and two cathodic reduction peaks at 2.0 and 1.3 V for FeS_2 with metal additives.The addition of 5wt% Co and 3wt% Ni resulted in an enhancement of the first discharge capacity giving 571 and 844mAh/g respectively at 0.1C-rate.The cycle performance was also enhanced remarkably by the addition of these electrically conductive transition metals in the active material.FeS_2 with 5wt% Co exhibited a stable cycle performance delivering a reversible capacity of 338mAh/g(37.8% of theoretical capacity)after 20 cycles.

Low Phase Noise VCO using Novel Harmonic Control Circuit Based on Quad-band Composite Right/Left-handed Transmission Line

In this paper, a novel Voltage-Controlled Oscillator （VCO） using the harmonic control circuit based on the quad-band Composite Right/Left-Handed （CRLH） Transmission Line （TL） is presented to reduce the phase noise without the reduction of the frequeacy tuning range and miniaturizing the circuit size. The phase noise has been reduced by the quad-band harmonic control circuit which has the short impedance for the second- and third- and fourth- and fifth-hannonic components. The CRLH TL with two Left-Handed （LH） （backward） and two Right-Handed （RH） （forward） pass bands are used to design the quad-band harmonic control circuit. The high- Q resonator has been used to reduce the phase noise, but it has the problem of the frequency timing range reduction. However, the frequency tuning range of the proposed VCO has not reduced because the phase noise has reduced without the high-Q resonator. The miniaturization of the circuit size is achieved by using the quad-band CRLH TL instead of the conventional RH TL, The phase noise of VCO is - 124.43～ - 122.67 dBc/Hz at 100 kHz in the tuning range of 5. 729 ～5.934 GHz.

INTERDECADAL CHANGE OF KOREA LANDFALLING TROPICAL CYCLONE FREQUENCY AND ITS POSSIBLE ASSOCIATION WITH PDO

The present study verified that Korea landfalling tropical cyclone(TC) frequency was rapidly increased since 1981 through the statistical change-point analysis. The increase was due to the formation of anomalous southerlies around Korea from the low latitude ultimately because anomalous cyclone was strengthened in East Asia continent due to the movement of western North Pacific subtropical high(WNPSH) to the east whereas anomalous anticyclone was strengthened in the western North Pacific. The anomalous southerlies played a role in steering flow that moved TCs generated in the subtropical western North Pacific to Korea. In order to determine the cause of strengthening of anomalous cyclone in East Asia continent, a snow depth during the preceding spring(March-May) was analyzed. The analysis result showed that most regions in East Asia had lower snow depth than that before 1981. Thus, anomalous cyclone can be developed in the region during summer due to heating in East Asia continent, which was started from the preceding spring, thereby forming a steering flow of anomalous southerlies that can move TCs into Korea. Furthermore, a correlation analysis between Pacific Decadal Oscillation(PDO) and Korea landfalling TC frequency verified that negative correlation was somewhat stronger after 1981.

INTERDECADAL VARIATION IN THE ACTIVITY OF TROPICAL CYCLONES AFFECTING KOREA

By performing a statistical change-point analysis of activities of the tropical cyclones(TCs)that have affected Korea(K-TCs),it was found that there was a signifi cant change between 1983 and 1984.During the period of 1984-2004(P2),more TCs migrated toward the west,recurved in the southwest,and affected Korea,compared to the period of 1965-1983(P1).These changes for P2 were related to the southwestward expansion of the subtropical western Pacifi c high(SWPH)and,simultaneously,elongation of its elliptical shape toward Korea.Because of these changes,the central pressure and lifetime of K-TC during P2 were deeper and longer,respectively,than fi gures for P1.This stronger K-TC intensity for P2 was related to the more southwestward genesis due to the southwestward expansion of the SWPH.The weaker vertical wind shear environment during P2 was more favorable for K-TC to maintain a strong intensity in the mid-latitudes of East Asia.

TROPICAL CYCLONE OCCURRENCE PROBABILITY FORECASTING MODEL IN THE WESTERN NORTH PACIFIC

A seasonal probability prediction model for tropical cyclone(TC)genesis in the western North Pacifi c(5°-25°N,110°-180°E)was developed using a simple logistic regression method.The predictors used in this model were total fi ve:850 h Pa relative vorticity,200-850 h Pa vertical wind shear,600 h Pa relative humidity,300 h Pa equivalent potential temperature,and sea surface temperature(SST).Four predictors except for SST were obtained from differences of spatial-averaged value between May and January,and time average of Ni?o-3.4 index from February to April was used to consider the SST effects.As a result of prediction for the TC genesis from June to December during 1951 to 2007,years that the model forecasts are 21 years among the total 28 years when the observed TC genesis frequency was higher than normal year.The overall predictability was about 75%,and the model was also verifi ed statistically through cross validation analysis using a method of the hindcast.

INTERANNUAL ANOMALY IN TROPICAL CYCLONE FREQUENCY AROUND KOREA BY WESTERN NORTH PACIFIC MONSOON

In this study, the correlation between the frequency of summer tropical cyclones(TC) affecting areas around Korea over the last 37 years and the western North Pacifi c monsoon index(WNPMI) was analyzed. A clear positive correlation existed between the two variables, and this high positive correlation remained unchanged even when excluding El Ni?o-Southern Oscillation(ENSO) years. To investigate the causes of the positive correlation between these two variables, ENSO years were excluded, after which the 8 years with the highest WNPMI(strong WNPM phase) and the 8 years with the lowest WNPMI(weak WNPM phase) were selected, and the average difference between the two phases was analyzed.In the strong WNPM phase, TCs usually occurred in the eastern waters of the tropical and subtropical western North Pacifi c, and tended to pass the East China Sea on their way north toward Korea and Japan. In the weak WNPM phase, TCs usually occurred in the western waters of the tropical and subtropical western North Pacifi c, and tended to pass the South China Sea on their way west toward the southeastern Chinese coast and the Indochina peninsula. Therefore, TC intensity was higher in the strong WNPM phase, during which TCs are able to gain suffi cient energy from the sea while moving a long distance to areas nearby Korea. TCs also tended to occur more often in the strong WNPM phase.In the difference between the two phases regarding 850 h Pa and 500 h Pa streamline, anomalous cyclones were reinforced in the tropical and subtropical western North Pacifi c, while anomalous anticyclones were reinforced in mid-latitude East Asian areas. Due to these two anomalous pressure systems, anomalous southeasterlies developed in areas near Korea, with these anomalous southeasterlies playing the role of anomalous steering fl ows making the TCs head toward areas near Korea. Also, due to the anomalous cyclones developed in the tropical and subtropical western North Pacifi c, more TCs could occur in the strong WNPM phase.