Ohyung Kwon

Realization of High Luminous Efficacy at Low Voltages in the Plasma Display Panel With SrO–MgO Double Layer

We have applied a double protecting layer consisting of SrO and MgO to a plasma display panel. The top MgO layer protects the underlying SrO from contamination by H2O or CO2 when exposed to air and enables it to function as the main cathode material after the aging process, which partially removes the MgO layer. We have confirmed that the adoption of a double SrO-MgO layer results in a considerable reduction in driving voltage and improvement in luminous efficacy simultaneously.

Mechanism of high luminous efficacy in plasma display panel with high secondary electron emission coefficient cathode material analyzed through three-dimensional fluid model simulation

The mechanism to realize high luminous efficacy in a plasma display panel fabricated with a cathode material possessing a high secondary electron emission coefficient (γ) for Ne and Xe ions was studied via three-dimensional numerical simulation. When a high γ cathode material is used, the increased electron heating efficacy is responsible for increasing vacuum ultraviolet (VUV) efficacy with 10% Xe content gas. However, the continued availability of sufficient secondary electrons during the dynamic moving phase of the cathode sheath in which the electric field remains weakened causes increasing VUV efficacy with 30% Xe content gas. It was found that the improvement of the luminous efficacy of the plasma display panel with a high γ cathode material is maximized under the condition of high Xe content gas because of the simultaneous increase of the electron heating efficacy and Xe excitation efficacy.

7.2: Address Discharge Characteristics of High Luminous Efficacy PDP with SrO Protecting Layer

We have achieved low voltage driving and high luminous efficacy by applying SrO protecting layer in PDP. Especially its low voltage characteristics can make it possible to use very high Xe content such as 30% gas at the voltage levels which currently commercialized PDP use. The use of SrO protecting layer can reduce the firing voltage not only between sustain electrodes but also between address and scan electrodes, so that the threshold voltage VAY as well as the address delay in the SrO panel with Xe 30% could be made comparable to those in the MgO panel with Xe 10% with the appropriate modifications in the ramp reset waveform.

Application of MgCaO Cathode Layer to Plasma Display Panel for High Luminous Efficacy

We have studied the characteristics of the application of a high-gamma cathode material to a plasma display panel (PDP) for the improvement of the secondary electron emission property and consequent luminous efficacy. It had been found that the PDP with the MgCaO cathode layer and the SiO2 diffusion barrier, which can block the impurity diffusion from the underlying dielectric layer, is stable during the normal fabrication process and showed improved luminous efficacy at a lower sustain voltage compared with those of the conventional PDP with MgO.

The Effects of Electrode Configuration on the Luminance and Luminous Efficacy of Mercury-Free Flat Fluorescent Lamp

To obtain highly efficient and stable discharges in mercury-free flat fluorescent lamps (MFFLs), the effects of the main electrode configuration on the electro-optical characteristics such as the operating voltage margin, luminance, and luminous efficacy are investigated. The spatiotemporal characteristic of the infrared emission from discharges in different electrode configurations (conventional coplanar, counter, and combination discharges) is also studied with an intensified charge-coupled device camera to see the differences with the electrode configuration variation. The MFFL having the combination electrode configuration with Ne-30% Xe gas mixture and a total pressure of 13.3 kPa showed high luminance from 3102 to 22 067 cd/m2 and high luminous efficacy from 49 to 93.5 lm/W for the warm white daylight with a color coordinate of (0.36, 0.36).

The role of a diffusion barrier in plasma display panel with the high gamma cathode layer

Plasma display panel (PDP) with MgO-SrO double cathode layer and SiO2 diffusion barrier is proposed to make the SrO layer free of contaminations. Time of flight-secondary ion mass spectrometry (TOF-SIMS) analysis shows the diffusion of impurities, like Na and K, can be effectively blocked while a new SrO layer is formed on top of the MgO layer. This structure shows that high Xe gases can be used to improve the luminous efficacy 2.3 times and decrease the voltage margin more than 10 V compared to the conventional PDP using Ne-Xe 15%. The aging time was also significantly decreased to 3–4 h.

Discharge characteristics of He–Ne–Xe gas mixture with varying Xe contents and at varying sustain electrode gap lengths in the plasma display panel

The discharge characteristics of He–Ne–Xe gas mixture in the plasma display panel were investigated using a two-dimensional numerical simulation to understand the effects of adding He and varying the Xe contents in the gas mixture, and also varying sustain electrode gap. With 5% Xe content and 60 μm sustain electrode gap, decreased ionization led to the improvement of the vacuum ultraviolet (vuv) efficacy at increasing He mixing ratios. However, at 20% Xe content and 60 μm sustain electrode gap, increased electron heating improved the vuv efficacy until the He mixing ratio reached 0.7, but the efficacy decreased beyond the ratio of 0.7 due to the increased ionization of Xe atoms. At 5% Xe content and 200 μm sustain electrode gap, the vuv efficacy increased as a result of increased electron heating at the gap space at increasing He mixing ratios.

Dry etching characteristics of TaN absorber for extreme ultraviolet mask with Ru buffer layer

The extreme ultraviolet (EUV) mask using reflective optics has a structure totally different from that of the conventional mask. This study investigated the dry etching characteristics of the EUV mask layer in which TaN and Ru were used as the absorber and buffer layer, respectively. The TaN absorber etching requires high etch selectivity of TaN over Ru to achieve the high EUV reflectivity. In this work, the TaN etching rate was investigated with various halogen gases in the capacitively coupled plasma type etching system. The etching rates with the fluorinated gases were higher than that with the chlorinated gas. Ru could not be etched without oxygen in all of the considered etch gases. The etching rate of TaN and its etch selectivity to Ru were increased with the increase of RF power, pressure and SF6 gas flow ratio. When the real EUV mask specimens were 100% over etched under the highest selectivity etching condition, the Ru buffer layer still remained, which was confirmed by x-ray photoelectron spectr...

Discharge characteristics of mercury-free flat fluorescent lamps with various electrode configurations analysed through a two-dimensional fluid model simulation

The discharge characteristics and factors related to the luminous efficacy of mercury-free flat fluorescent lamps (MFFLs) with three different types of coplanar, counter and combination electrode configurations were studied via a two-dimensional numerical simulation. The spatiotemporal distributions of the potential, electric field, electron density, Xe** density and current waveforms of the MFFLs were obtained and analysed. The MFFL with the combination electrode configuration shows the highest vacuum ultraviolet (VUV) efficacy value. The vertical electrode in the MFFL with the combination electrode configuration prevents the electric field at the gap space from decreasing rapidly, and extends the discharge path. The effects of the vertical electrode help one to increase the Xe excitation efficacy. In addition, a new auxiliary electrode was proposed in the original MFFL with the combination electrode configuration. The MFFL with the new auxiliary electrode has broader distributions of electrons and Xe** species, and a higher VUV efficacy value than the original MFFL with the combination electrode configuration at the same voltage.

Effect of the Driving Waveform With Negative-Going Ramp on the Address Discharge Characteristics of Plasma Display Panel With High-Gamma Cathode Material

The address discharge characteristics of the plasma display with a MgO single cathode layer and the one with a MgO-SrO double cathode layer were investigated. In particular, the conventional waveform with a positive-going ramp and the proposed waveform with a negative-going ramp were applied in order to demonstrate that the polarity of the scan electrode during the reset period affects the dynamic voltage margin and the address discharge time lag. It was confirmed that the total address discharge time lag of the plasma display with the MgO-SrO double cathode layer decreased by about 550 ns by applying the proposed waveform with the negative-going ramp.