Publication detail

Near-field measurement of ZnS:Mn thin-film electroluminescent devices

GRMELA, L. KALA, J. TOMÁNEK, P.

Original Title

Near-field measurement of ZnS:Mn thin-film electroluminescent devices

Czech Title

Měření ZnS:Mn tenkovrstvých elektroluminescentních zařízení v blízkém poli

English Title

Near-field measurement of ZnS:Mn thin-film electroluminescent devices

Type

conference paper

Language

en

Original Abstract

Thin film electroluminescent devices (TFELD) of inorganic phosphors have become of great interest since they offer a possible means of achieving a high-resolution, light-weight, compact video display panel for computer terminals or TV screens. Current inorganic TFEL phosphors are composed of II-VI wide bandgap semiconductor hosts (ZnS, SrS) which provide hot carriers (>2 eV) which impact excite luminescent centers (Mn, Tb, Ce, Cu). Sufficient hot carrier generation requires high field strengths (>1 MV/cm) exceeding the breakdown field of the phosphor thin film. An AC-biased dielectric/phosphor/dielectric layered structure allows reliable high field operation by current-limiting the electrical breakdown of the phosphor layer [1]. From a device point of view, a hysteresis in the brightness vs. applied voltage response curve is the most important advantage of AC-TFEL devices for large-area applications. In spite of the fact that the brightness of a memory-type EL is, in general, lower than that of non-memory ones, their advantage lies in the possibility of operating on an arbitary number of pixels in the matrix addressing mode at the same brightness level as the one-pixel device. Thus, memory devices are potentially more suitable for large area display operation [2]. To contribute to the local investigations of memory-type ZnS:Mn electroluminescent devices characteristics, we have been interested in the local electro-optical phenomena near the surfaces at the distances much less than the radiation wavelength. Beside a purely fundamental interest this is connected to the vigorous development of the scanning near-field optical microscopy. By scanning a 100 um x 100 um ACTFEL radiative surface in optical near-field we have found a pronounced hysteresis effect in the brightness vs. pulse width (B-W) response curve for memory-type ACTFEL devices driven near the threshold voltage. Moreover, we have investigated the dependence of the B-W characteristics on the ambient temperature and on the film thickness of the ZnS:Mn layer. The variations of the response times with respect to these parameters were also studied. The results will be reported in the paper.

Czech abstract

Tenkovrstvé elektroluminiscenční zařízení (TFELD) nabývají stále většího významu hin film electroluminescent devices (TFELD, protože umožňují v displejích dosáhnout vyššího rozlišení, nižší hmotnosti. Článek přináší náš příspěvek k této problematice. Zabývali jsme se zejména studiem lokálních elektrooptických jevů v blízkosti povrchu luminoforu (ve vzdálenosti << lambda). Skenováním plochy 100 um x 100 um vyzařujícího povrchu jsme nalezli výrazný hysterezní jev v závislosti jasu na šířce pulsu (B-W křivka) Dále jsme se zabývali studiem závisloti charakteristik B-W na okolní teplotě a tloušťce vrstvy ZnS:Mn a změnami odezev závisejících na těchto parametrech.

English abstract

Thin film electroluminescent devices (TFELD) of inorganic phosphors have become of great interest since they offer a possible means of achieving a high-resolution, light-weight, compact video display panel for computer terminals or TV screens. Current inorganic TFEL phosphors are composed of II-VI wide bandgap semiconductor hosts (ZnS, SrS) which provide hot carriers (>2 eV) which impact excite luminescent centers (Mn, Tb, Ce, Cu). Sufficient hot carrier generation requires high field strengths (>1 MV/cm) exceeding the breakdown field of the phosphor thin film. An AC-biased dielectric/phosphor/dielectric layered structure allows reliable high field operation by current-limiting the electrical breakdown of the phosphor layer [1]. From a device point of view, a hysteresis in the brightness vs. applied voltage response curve is the most important advantage of AC-TFEL devices for large-area applications. In spite of the fact that the brightness of a memory-type EL is, in general, lower than that of non-memory ones, their advantage lies in the possibility of operating on an arbitary number of pixels in the matrix addressing mode at the same brightness level as the one-pixel device. Thus, memory devices are potentially more suitable for large area display operation [2]. To contribute to the local investigations of memory-type ZnS:Mn electroluminescent devices characteristics, we have been interested in the local electro-optical phenomena near the surfaces at the distances much less than the radiation wavelength. Beside a purely fundamental interest this is connected to the vigorous development of the scanning near-field optical microscopy. By scanning a 100 um x 100 um ACTFEL radiative surface in optical near-field we have found a pronounced hysteresis effect in the brightness vs. pulse width (B-W) response curve for memory-type ACTFEL devices driven near the threshold voltage. Moreover, we have investigated the dependence of the B-W characteristics on the ambient temperature and on the film thickness of the ZnS:Mn layer. The variations of the response times with respect to these parameters were also studied. The results will be reported in the paper.

Keywords

ZnS:Mn thin film, near-field measurement, brightness, pulse width, ambient temperatue

Released

10.09.2006

Publisher

EPFL Lausanne

Location

Lausanne, Switzerland

Pages from

326

Pages to

328

Pages count

3

URL

BibTex


@inproceedings{BUT19858,
  author="Lubomír {Grmela} and Jaroslav {Kala} and Pavel {Tománek}",
  title="Near-field measurement of ZnS:Mn thin-film electroluminescent devices",
  annote="Thin film electroluminescent devices (TFELD) of inorganic phosphors have become of great interest since they offer a possible means of achieving a high-resolution, light-weight, compact video display panel for computer terminals or TV screens.  Current inorganic TFEL phosphors are composed of II-VI wide bandgap semiconductor hosts (ZnS, SrS) which provide hot carriers (>2 eV) which impact excite luminescent centers (Mn, Tb, Ce, Cu). Sufficient hot carrier generation requires high field strengths (>1 MV/cm) exceeding the breakdown field of the phosphor thin film. An AC-biased dielectric/phosphor/dielectric layered structure allows reliable high field operation by current-limiting the electrical breakdown of the phosphor layer [1].

From a device point of view, a hysteresis in the brightness vs. applied voltage response curve is the most important advantage of AC-TFEL devices for large-area applications. In spite of the fact that the brightness of a memory-type EL is, in general, lower than that of non-memory ones, their advantage lies in the possibility of operating on an arbitary number of pixels in the matrix addressing mode at the same brightness level as the one-pixel device. Thus, memory devices are potentially more suitable for large area display operation [2].

To contribute to the local investigations of memory-type ZnS:Mn electroluminescent devices characteristics, we have been interested in the local electro-optical phenomena near the surfaces at the distances much less than the radiation wavelength. Beside a purely fundamental interest this is connected to the vigorous development of the scanning near-field optical microscopy.

By scanning a 100 um x 100 um ACTFEL radiative surface in optical near-field we have found a pronounced hysteresis effect in the brightness vs. pulse width (B-W) response curve for memory-type ACTFEL devices driven near the threshold voltage. Moreover, we have investigated the dependence of the B-W characteristics on the ambient temperature and on the film thickness of the ZnS:Mn layer. The variations of the response times with respect to these parameters were also studied. The results will be reported in the paper.

",
  address="EPFL Lausanne",
  booktitle="Near-field optics, Nanophotonics and Related Techniques",
  chapter="19858",
  institution="EPFL Lausanne",
  year="2006",
  month="september",
  pages="326--328",
  publisher="EPFL Lausanne",
  type="conference paper"
}