Kyohei Yoshino

Effects of Wall Charge on Firing Voltage and Statistical Delay Time in Alternating-Current Plasma Display Panels

The effects of wall charge on firing voltage, Vf, and the statistical delay time of discharge, ts, in plasma display panels were investigated. Vf, i.e., the ion-induced secondary electron emission, is independent of both the polarity and amount of wall charge. In contrast, ts, i.e., the exoelectron emission, strongly depends on the wall charge and is smaller for a high positive wall charge, revealing the coexistence of trapped electrons and holes in the surface region. Positive charging of the MgO surface of the cathode side is effective to improve the response of the address discharge.

Application of ion scattering spectroscopy to measurement of surface potential of MgO thin film under ion irradiation

An experimental approach was proposed for the measurement of the surface potential (SP) induced on an insulator surface during ion irradiation by ion scattering spectroscopy (ISS). The resultant ISS spectra obtained for a MgO thin film of 600nm thickness on a Si substrate under 950eV He+ irradiation revealed that the surface is positively charged by approximately 230V. In addition, the onset energy of a secondary ion peak indicated a SP of approximately 205V. The present results confirmed that ISS is an effective technique for measuring the SP during ion irradiation.

In situ measurement of surface potential developed on MgO thin film surface under ion irradiation using ion scattering spectroscopy

The application of ion scattering spectroscopy (ISS) to the in situmeasurement of the surface potential developed on an insulator surface under positive ion irradiation was investigated. The ISS spectra measured for a MgO film of 600 nm thickness on a Si substrate by the irradiation of 950 eV He + ions revealed that the surface is positively charged by approximately 180 V. For accurate measurement of the surface potential, a correction to take into account the angular deflection of primary ions induced by the high surface potential is required. The dependence of the surface potential on the sample temperature revealed that no charging is induced above 700 ° C , indicating that accumulated charges can be removed by heating to 700 ° C . From the measurement of the ion-induced secondary electron yield using a collector electrode located in front of the sample surface, the surface potential and ion-induced secondary electron yield were found to be strongly affected by the experimental setup. Secondary electrons produced by the impact of slow positive secondary ions, the maximum energy of which corresponds to the surface potential, play an important role when the bias voltage applied to the collector electrode is positively high for the present experimental setup. The surface potential developed on the surface of MgO films of 600 and 200 nm thickness was measuredin situ, revealing that the amount of accumulated charges and the time required to attain the steady state of charging are slightly dependent on the beam current of primary ions and strongly dependent on the thickness of the MgO film. The present results confirmed that the application of ISS has high potential for investigating charging phenomena and the secondary electron emission from insulator surfaces under positive ion irradiation.

Accumulation and Decay Characteristics of Exoelectron Sources at MgO Protective Layer Surface in Alternating-Current Plasma Display Panels

The accumulation and decay characteristics of exoelectron sources at a MgO protective layer surface in alternating-current plasma display panels (AC-PDPs) were investigated. The positively charged MgO surface provides a larger number of exoelectrons than the negatively charged surface, indicating that electrons trapped in shallow carrier traps coexist with trapped holes, and exoelectrons are emitted through Auger and/or photoionization processes after their recombination. The exoelectron sources are accumulated by sustain discharges and always decay. The halflife of the decay of the exoelectron sources is relatively long, of the order of a few tens of ms, confirming that the exoelectron emission property at the address discharge in a certain television (TV) field is strongly affected by sustain firings in the previous two TV fields or more. The effects of such a long-term decay of the exoelectron sources should be taken into consideration when designing the driving waveforms of AC-PDPs. # 2010 The Japan Society of Applied Physics

Improvement in Discharge Delay Time by Accumulating Positive Wall Charges on Cathode MgO Protective Layer Surface in Alternating-Current Plasma Display Panels

The improvement in discharge delay time by accumulating positive wall charges on a cathode MgO protective layer surface in plasma display panels (PDPs) was investigated. The number of exoelectrons emitted from the cathode MgO surface, which trigger the discharge, increases with the accumulation of positive wall charges on the cathode MgO surface, thereby reducing both the statistical and formative delay times, ts and tf, respectively, of the address discharge. The correlations between exoelectron emission and ts and tf were investigated, revealing that the address discharge is triggered by multiple exoelectrons. In addition, it is found that exoelectron emission plays an important role in wall charge leakage during the address period. The present results confirmed that the accumulation of positive wall charges on the cathode MgO protective layer surface is effective for improving the discharge delay times ts and tf in not only PDPs but also common dielectric barrier discharge.

Surface characterization of MgO:Al,N films with meta‐stable de‐excitation spectroscopy and x‐ray photoelectron spectroscopy

— It is shown that meta-stable de-excitation spectroscopy (MDS) is one of the most useful characterization methods to analyze the interaction between the discharge gas and the surface of the material and is applied to MgO:Al,N films. From the results of the measurement and analysis of helium MDS and the in-situ discharge experiment, it is confirmed that the limited composition films of MgO:Al,N have potentially a larger secondary-electron-emission coefficient (γ) compared with that of MgO. The improvement in γ is caused by the electron-occupied tailing state at around the top of the valence band which is generated by the introduction of Al,N to MgO films. Also, the O1s spectra measured by x-ray photoelectron spectroscopy (XPS) shows that the stable surfaces are formed with the introduction of Al,N to MgO films.

44.3: Investigation of Effects of Heating in Air on Ionization Potential of MgO and CaO Films using Metastable De‐excitation Spectroscopy

Effects of heating in air on the ionization potentials, Eip, of MgO and CaO films were investigated using metastable de-excitation spectroscopy (MDS). The difference in Eip between samples with and without heating in air was found to be small for MgO and significant for CaO. In addition, the difference in the ion-induced secondary electron yield, γ, which is expected from Eip determined from the MDS spectra, between samples with and without heating in air qualitatively agrees with that expected from the measurement of the firing voltage using a test panel. The present results conformed that MDS is effective to evaluating γ of the protective layer used in plasma display panels.