S.T. de Zwart

Gas flow dynamics in laser ablation deposition

The gas flow dynamics of laser ablation plumes is investigated experimentally and theoretically. Experimentally, angular‐resolved time‐of‐flight (ARTOF) measurements are performed on a model system (laser etching of copper in a chlorine environment). The TOF spectra obtained can be fitted by elliptical Maxwell–Boltzmann distributions on a stream velocity. Theoretically, an analytical model is constructed, based on the hydrodynamical problem of an expanding elliptical gas cloud. The model allows semiquantitative prediction of ARTOF distributions and angular intensity distributions. Observed trends in laser ablation deposition such as independence of the angular intensity distribution on mass of the atom and laser fluence, and dependence of the angular distribution on spot dimensions are explained.

Improvement of the discharge efficiency in plasma displays

The dependence of the efficacy of an alternating current surface-discharge plasma display panel on the gas pressure is investigated for several Xe–Ne gas mixtures. In monochrome green 4 in. test panels the efficacy trends and emission spectra are examined for increasing gas pressure and/or Xe concentration. The measured panel efficacy and emission characteristics are compared with the results of a numerical discharge model. It is found that the discharge efficiency for the cell geometry used in present-day commercial products can be increased significantly by using a larger Xe partial pressure. An increase of the electron heating efficiency and of the Xe excitation efficiency contribute about equally to the efficacy increase. The contribution of the increasing Xe dimer radiation fraction to the efficacy improvement is relatively small. These findings are applied in a 4 in. color test display with a design that resembles the one used in present-day commercial products and contains a gas mixture of 13.5% Xe...

Materials with a high secondary-electron yield for use in plasma displays

Reduction of the firing voltage in plasma display panels calls for electrode coatings with a high secondary-electron yield. We have explored a range of materials that exhibit very low firing voltages, and a 50% reduction has been achieved relative to the best quality MgO. It is further shown that a high electron emission yield originates from both ion- and photon-induced processes, and is strongly influenced by the electronic structure of the material in terms of band gap and electron affinity.

Discharge efficiency in plasma displays

The dependence of the panel efficacy of an alternating current-surface-discharge plasma display on the input power is investigated. Test panels with a design resembling the one used in main stream commercial products are used. The input power is varied in two ways: namely by changing the dielectric layer capacitance (thickness) and by changing the sustain voltage. An interesting different behavior is found: for increasing capacitance the efficacy decreases markedly, whereas for increasing sustain voltage the efficacy increases slightly. The different behavior is attributed to changes in the ion heating losses. It is found that plasma saturation, which implies a fundamental trade-off between luminance and efficacy, is not significant at practical input power values. A high luminance and a high efficacy are concurrent for a plasma panel design with a low dielectric layer capacitance and a high sustain voltage.

Description of the influence of charging on the measurement of the secondary electron yield of MgO

Abstract The influence of charging on the secondary electron emission yield (σ) measurements of MgO is studied. This is done by measuring σ as a function of the primary energy (Ep) of the electron beam of thin layers of MgO deposited on Si. At high Ep, σ decreases when the primary current or the layer thickness increases. At low Ep, we find that σ increases somewhat due to charging. As a result of the measurement technique σ can become smaller than 1, even when Ep is in the energy range where σ is expected to be larger than 1. Furthermore, we observe for some samples the onset of a conduction mechanism at high primary currents. Monte Carlo calculations show that a potential barrier in front of the sample can arise, leading to a partial recapture of the generated secondary electrons. This causes σ to decrease at high Ep. A simplified analytical model is presented to calculate the effect of charging of the sample on the measured value of σ.

High-Xe-content high-efficacy PDPs

The trade-off between PDP efficacy improvement and driving voltages was investigated for several design factors. It was found that for a proper combination of an increased Xe content, cell design, and the use of a TiO 2 layer combined with non-saturating phosphors, a large increase in both efficacy and luminance can be realized at moderately increased drive voltages. In a 4-in. color test panel, a white efficacy of 5 lm/W and a luminance of 5000 cd/m 2 was obtained for sustaining at 260 V in addressed condition.

Modes in electron-hopping transport over insulators sustained by secondary electron emission

A general formalism for hopping electron transport over insulators sustained by secondary electron emission is presented. Steady-state electron transport takes place when the charging of the insulator, which turns out to be self-stabilizing, is such that the average secondary electron yield becomes equal to unity. The steady-state potential distribution for the electron transport is determined for various insulating geometries with the aid of Monte Carlo calculations and compared with the low-hopping approximation. The Monte Carlo results show that the steady-state potential distribution can exhibit several interesting features such as spontaneous symmetry breaking of statistical origin and the occurrence of local repulsive parts in the geometry. In several cases the numerical results, including the above two features, are found to agree well with the results of experiments.

Improvement of luminance and luminous efficacy in PDPs

The dependence of PDP luminance and efficacy on the input power was investigated for several Xe-Ne gas mixtures. The input power was varied in two ways: namely, by changing the dielectric-layer capacitance (thickness) and by changing the sustain voltage. A distinctly different behavior was found; for increasing capacitance the efficacy decreases markedly, whereas for increasing sustain voltage the efficacy increases. A design window comprising the combination of a high Xe concentration and a high sustain voltage was suggested. In this window, a high luminance and a high efficacy are concurrent. A 4-in, test panel with 10% Xe in Ne has been realized showing a white luminance of 2040 cd/m 2 and an efficacy of 2.3 lm/W for continuous sustaining at 50 kHz with a sustain voltage of 225 V.

Basics of electron transport over insulators

Abstract The basic mechanism of electron transport in vacuum through insulating structures is discussed. The transport is based on a self-regulating secondary electron emission process. A general description of the transport process is presented. Three methods to model steady-state transport are briefly reviewed. The features are discussed in the light of application in displays. Also, non-steady-state effects and the role of space charge are addressed.

20.1: Locally Switchable 3D Displays

3D displays will drastically enhance the viewing experience of future displays for many applications. Unfortunately, 3D displays generally have a lower resolution since the pixels are divided over more views. Therefore, some 3D displays have the opportunity to switch between 2D and 3D mode such that either natural 3D images or high-resolution 2D images can be displayed. However, especially for mobile applications it is advantageous to be able to display 3D and 2D at the same time. In this paper we will discuss the design and driving of locally switchable lenticulars, which combines perfect high-resolution 2D with natural 3D areas.