field-emission displays (fed´s) - fh-muenster.de · 1. working principle 4 generation of...

Stephanie Dirksmeyer, 671197

Field-Emission Displays

(FED´s)

Contents

2

1. Working Principle

2. Applied Phosphors

2. Features

3. Developments

Stephanie Dirksmeyer | Field-Emission Displays 26.06.2016

http://www.prad.de/new/news/shownews_tv871.html


3 Stephanie Dirksmeyer | Field-Emission Displays 26.06.2016

generation of electrons

acceleration of electrons

excitation of phosphors

emission by phosphors

comparable to cathode ray tubes!

taken from: http://elektroniktutor.de/technologien/te_pict/microtip.gif


4

generation of electrons: via field emission

electrical fields above 109 V/cm set free electrons from metal surfaces via tunneling


http://en.wikipedia.org/wiki/File:Fig216_Field_Emission.PNG

potential drop due to E-field


5

high field strength is reached by special geometry

high density of field lines at sharply curved surfaces


http://cnx.org/content/m42317/latest/?collection=col11406/latest


6

use of Spindt-type emitters

cones of molybdenummechanically and thermally stable

low work function

diameter at base and height: ca. 1 µmapplication of field via extraction grid/ gate (U ≈ 50 V)arranged as array: up to 1000 emitters per pixel


http://en.wikipedia.org/wiki/File:Fig218_Field_Emitter_Array.PNG


7

further acceleration towards cathode(V > 500 V)gate is used for easier controlexcitation of phosphor pixels

alternative emitter materials: carbon nanotubes (CNT´s)

silicon (in the beginning)



8

requirements to phosphors:

colour point (red, blue, green pixels)high quantum efficiencyshort decay timestability

in general the same as for CRT displays



9

special requirement to FED phosphors:excitation energy is lower(30 kV in CRT´s ↔ max. 8 kV in FED´s)

excitation only at surface

decreasing number of involved luminescent centers: efficiency saturation

more defects at surface: quenching

high current density: fast degradation


2. Applied phosphors

10

suited phosphors:

use of oxidic hostsor inorganic protective coating


red green blueY2O3:Eu ZnO:Zn ZnGa2O4

YVO4:Eu Gd2O2S:Tb Y2SiO5:Ce


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mechanism of cathodoluminescence

excitation of the host formation of excitonsluminescent centres trap excitonsrelaxation under luminescence under 3 mechanisms

centre luminescence

characteristic luminescence

donor-acceptor luminescence



12

mechanisms of luminescencecentre luminescence:

at an activator ion influenced by its environment (crystal field theory)

broad bands

typical for transition metals (e.g. Mn2+) and complex anions (e.g. (VO4)3-)

characteristic luminescence:based on f-f- transitions of rare earth ions

line emitters



13

donor-acceptor luminescence:trapping of single charge carriers

recombination under luminescence

broad, unstructured bands due to vibrations


3. features

14

advantages

flat screen: ca. 2 mmself-emissivewide viewing angle (no polarisation filters)quick response time: µs-rangelow power consumptionhigh contrast (black matrix)

experience from CRT-technique can be adapted


3. features

15

disadvantages

high accuracy needed in productionsealing: high vacuum insidestability of phosphors


3. Developments

16

effect of field emission known since 19th centurytheoretical explanation 1928 by Fowler and Nordheimearly use in field-emission microscopedevelopment of FED technique since ≈ 1990 by different companiesmany campaigns stoppedonly prototypes were build

today research on CNT emitters


demonstration by Sonyhttp://www.prad.de/new/news/shownews_tv871.html

Sources

17

Bredol, M., Kynast, U., & Ronda, C. (1994). Leuchtstoffe für Kathodenstrahlröhren. Angewandte Chemie, S. 36 - 43.

Cathey, D. (1995). Field Emission Display. VLSI Technology, Systems and Applications, (S. 131 - 136). Taipei.

Itoh, S., & Tanaka, M. (4 2002). Current Status of Field-Emission Displays. Proceedings of the IEEE(90).

Jüstel, T., Feldmann, C., & Ronda, C. (2000). Leuchstoffe für aktive Displays. Physikalische Blätter(56), S. 55 - 58.

Jüstel, T., Nikol, H., & Ronda, C. (1998). New Developments in the Field of Luminescent Materials for Lightning and Displays. Angewandte Chemie, International Edition(37), S. 3084 - 3103.

Shah, I. (6 1997). Field-emission displays. Physics World.

Mietke, D. www.elektroniktutor.de. Abgerufen am 11. 4 2014 von http://elektroniktutor.de/technologien/fed.html

www.cnx.org. (6. 6 2012). Abgerufen am 11. 4 2014 von http://cnx.org/content/m42317/latest/?collection=col11406/latest

http://de.wikipedia.org/wiki/Feldemission

http://en.wikipedia.org/wiki/Field_emission_display#History


field-emission displays (fed´s) - fh-muenster.de · 1. working principle 4 generation of...

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