Solid State Phenomena Vols. 124-126

Abstract: Electrical, optical, and structural properties of amorphous indium zinc oxide (IZO) anode films grown on flexible polycarbonate (PC) substrate were investigated. The x-ray diffraction (XRD) result shows that the IZO film grown at room temperature is complete amorphous structure due to low substrate temperature. A sheet resistance of 34.1 ,/
, average transmittance above 88.9% in visible range, and root mean spare roughness of 3.5~10.5 Å were obtained even in the amorphous IZO anode film grown on PC substrate at room temperature. It is shown that the Ir(ppy)3 doped-flexible organic light emitting diode (OLED) fabricated on the amorphous IZO anode exhibit comparable current-voltage-luminance characteristics as well as external quantum efficiency and power efficiency to OLED fabricated on conventional ITO/glass substrate. These findings indicate that the IZO anode film is a promising anode material for the fabrication of flexible OLEDs.

Abstract: ITO monolayer and ITO/Ag/ITO multilayer thin films are prepared by D.C. magnetron sputtering method, optical and electrical properties were estimated with different crystalline properties and microstructures. The coated Ag layer thickness was around 50
, and the surface of ITO/Ag/ITO thin film had the very fine island morphology. The growth of columnar phase was inhibited, and most of phases were amorphous. The carrier concentration increased above 10 times because of the effect of Ag layer, and the observed sheet resistance gave much lower value of below 4 / compared to that of coated crystalline ITO thin film that was 10 / , and the transmittance was 80%.

Abstract: We report the effects of instability with gate dielectrics of pentacene thin film transistors (OTFTs) inverter circuits. We used to the UV sensitive curable resin and poly-4-vinylphenol(PVP) by gate dielectrics. The inverter supply bias is VDD= -40 V. For a given dielectric thickness and applied voltage, pentacene OTFTs with inverter circuits measurements field effect mobility, on-off current ratio, Vth. The field effect mobility 0.03~0.07 cm2/Vs, and the threshold voltage is -3.3 V ~ -8.8 V. The on- and off-state currents ratio is about 103~106. From the OTFT device and inverter circuit measurement, we observed hysteresis behavior was caused by interface states of between the gate insulator and the pentacene semiconductor layer.

Abstract: The mechanism of failure of patterned ITO electrodes on PET was investigated under static and cyclic bending in the mechanical stress mode. When mechanical stresses are increased, two types of micro-cracks are observed depending on the stress modes. The direction of the micro-crack in ITO electrodes is perpendicular to the load for the static mode. The electrical resistance of an ITO electrode is related to the density of the micro-cracks and failure mechanism of ITO electrode.

Abstract: The present study is mainly focused on the evaluation of interface reaction between ceramic fillers and phosphate glass matrix for barrier ribs in PDP. The samples were prepared by dry milling for frits with a mean particle size(d50) of 1-2㎛. The frit was mixed with ceramic fillers (Al2O3, ZnO) and was fired at 550°C for 30 minutes. Interface reaction was observed by measuring the weight change of fired samples as a function of immersion time in 90°C de-ionized water and in 60°C acid solution. Fired samples were characterized by differential thermal analyzer, scanning electron microscopy, X-ray diffraction and ion dissolution was analyzed by inductive coupled plasma measurement. The results suggest that properties of barrier rib depend on the crystallization behavior and interface reaction between the fillers and the glass matrix.

Abstract: Tb3Al5O12:Ce (TAG:Ce) phosphor particles were prepared by spray pyrolysis process. The TAG:Ce phosphor particles prepared by spray pyrolysis had good characteristics such as fine size, narrow size distribution, and high photoluminescence intensity under blue light excitation. The TAG:Ce phosphor particles had the maximum photoluminescence intensity after post-treatment at 1550oC under reducing atmosphere. The photoluminescence intensity of the prepared TAG:Ce phosphor particles was 85% of the optimized YAG:Ce phosphor particles.

Abstract: In order to improve long term stability of a-Si:H TFT for AM-OLED application a new driving method compensating Vth shift requires a new device structure of which hole injection is enhanced. ITO film was investigated for the hole injection material because it is essential material for display devices and has high work function favorable for hole injection. From I-V characteristics of TFTs with two types of source and drain material, i.e. Cr and ITO, the contact properties were measured and compared. Although electron injection property of ITO was worse than Cr, hole injection property was comparable to that of Cr.

Abstract: Molecular ordering and current-voltage characteristics of vacuum-deposited m-MTDATA(4,4’,4’’-tris[N,-(3-methylphenyl)-N-phenylamino]triphenylamine), widely used as a hole injection material in OLEDs, thin films were investigated. Molecular ordering was induced by thermal annealing under electromagnetic field after deposition of m-MTDATA onto the pre-patterned ITO glass. AFM and XRD analysis were employed to characterize the topology and molecular ordering of m-MTDATA thin films. The XRD and AFM results show that m-MTDATA can be molecularly ordered by means of thermal annealing under electromagnetic field. Thermal annealing at 100°C was desirable to get a high degree of molecular ordering with dendritic grains. It was shown that molecular ordering as well as larger dendritic grains in the thin films influenced on improving the current-voltage characteristics and increasing the leakage current of the ITO/m-MTDATA/Al device. Electromagnetic field improved the surface roughness, as well. It is regarded that Rpv seems more significant than the other roughness parameters. Significantly lower Rpv(peak-to-valley roughness) obtained by both thermal annealing and electromagnetic field resulted in enhancing the stability of the current ITO/m-MTDATA/Al device. Ra(average roughness) and Rrms(root-mean-square roughness), however, did not significantly relate with leakage current.

Abstract: Indium Tin Oxide (ITO) films were deposited on non-alkali glass substrate by magnetron sputtering using commercial ITO target (target A) and improved ITO target (target B). Depositions were carried out at total gas pressure (Ptot) of 0.5 Pa, substrate temperature (Ts) of RT ~ 300 °C, oxygen flow ratio [O2/(O2+Ar)] of 0 ~ 1.0% and dc power of 100W. Target B showed relatively higher stability in film resistivity with increasing sputtering time, i.e., erosion ratio of target surface. Optimum oxygen ratio to obtain the lowest resistivity was decreased with increasing substrate temperature. The lowest resistivity was 1.06x10-4 6cm for the film deposited using target B at O2/(O2+Ar) ratio of 0.05% and at Ts =300 °C.

Abstract: The chemical reaction between water and frit surface was determined using pH meter, ICP-MS, zeta-potential analyzer and FT-IR. With increasing the content of barium and boron of glass composition, the difference of water pH increased with different glass systems. During wet milling in aqueous solution, boron and barium of glasses dissolved. The values of zeta potential of lead and bismate frits were negative in water solution. Based on the results, when wet milling is used in water solution, the contents of barium and boron in a glass should be less than 10mol%.