IMV Europe 2001

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Project IST-2001-32793 1. Mar.2002 -
31.Aug.2004 New GaP grown by VGF for Light
Emitting Diodes - 1 -
New Gallium Phosphide grown by Vertical Gradient
Freeze Method for Light Emitting Diodes
(LEDs) LED direct conversion of electrical
energy to the light
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Project IST-2001-32793 1. Mar.2002 -
31.Aug.2004 New GaP grown by VGF for Light
Emitting Diodes - 2 -
WHY is LED so important that an IST project was
opened on this topic?   The answer is very
simple LEDs The Future of Lighting
(Electrical Line Magazine 9/10
1998) High-Brightness LEDs lighting up to the
future (III-Vs Review 1 2001) LEDs
represent a new modern alternative source for the
electrical lighting. And without electrical
lighting we can not image one single day in our
life, what is underlined with following figures
(P. Reppeto, 5/2002)     - overall market of
light sources is estimated to reach 12 billion,
   - nearly 20 of electrical load represents
lighting in residential buildings,
- over 60 of electrical load is used
for the lighting in non-residential buildings,
roads and outdoor
venues. APPLICATIONS
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Project IST-2001-32793 1. Mar.2002 -
31.Aug.2004 New GaP grown by VGF for Light
Emitting Diodes - 3 -

BENEFITS 1.      LEDs have a
lower power consumption. They are 10 to 50 times
more energy efficient, thus reducing the
operating costs by up to 90 . 2.      LEDs
give smaller heat generation. 3.      LEDs
provide the equivalent or better
lighting. 4.      LEDs provide the better
reliability. 5.      LEDs last an average of
100,000 hours (or about 10 years). 6.      LEDs
allow for smaller connectors and sockets. 7.     
LEDs are dimmable with the potentiometer. 8. 
 LEDs withstand shocks, vibrations, frequent
switching and temperature extremes that rapidly
incapacitate fragile incandescent
lamps. 9.     LEDs produce sharp, vibrant
colors, even pure white. LEDs are becoming the
tool for designers looking for new
creations in space and lighting. 10.  LEDs are
very fast. Their response times are 100 to 1,000
times faster than incandescent lamp so
there is no flicker just pure light.
CONCENTRATION on research in new lighting
technologies will bring for Europe the major
impact on competitiveness ?development of new,
modern, efficient and low costs materials and
processes will help
to bring manufacturing capacity back to Europe,
environment ? higher efficiency
of sources and better management and control of
lighting systems
will allow to slash the
electrical power consumption,
quality of life ?high quality lighting
products contribute to workplace safety and to
the benefit
of user's health and comfort.
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Project IST-2001-32793 1. Mar.2002 -
31.Aug.2004 New GaP grown by VGF for Light
Emitting Diodes - 4 -

• TYPICAL DIVISION OF LEDs
• The most currently used and produced visible
  LEDs can be divided according to these
  parameters
• - structure (type of epitaxial
  layer/substrate),
• color,
• luminous intensity

• Currently, Taiwan produces around 1.5 billion LED
  chips per month. The majority of these chips are
  used for low brightness applications, with
  around
• 40 of the volume accounted for standard GaP
  yellow and green,
• 25 for red emitting devices,
• 15 for GaAsP yellow, amber and orange,
• 20 of the LED chips are used for
  high-brightness applications, with 10 accounted
• for AlGaAs red and 5 IRED LEDs

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Project IST-2001-32793 1. Mar.2002 -
31.Aug.2004 New GaP grown by VGF for Light
Emitting Diodes - 5 -
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Project IST-2001-32793 1. Mar.2002 -
31.Aug.2004 New GaP grown by VGF for Light
Emitting Diodes - 6 -
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Project IST-2001-32793 1. Mar.2002 -
31.Aug.2004 New GaP grown by VGF for Light
Emitting Diodes - 7 -
TYPICAL CONSTRUCTION OF SHB-LEDs
1. Direct deposition on GaAs
2. Between AlInGaP and GaAs is Bragg
reflector deposited OSRAM (D)

• amber GaP/AlInGaP/GaAs LED with GaP window layer
  and with absorbing GaAs substrate (AS)
• amber GaP/AlInGaP/GaP LED with GaP window layer
  and with transparent GaP substrate (TS)

3. Reflector is created with metal bonding
technique OSRAM (D)
Industrially used only wafer bonding
technique LUMILEDS (USA)
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Project IST-2001-32793 1. Mar.2002 -
31.Aug.2004 New GaP grown by VGF for Light
Emitting Diodes - 8 -
Goal and Objectives of our Project
1. Development of a novel Gallium Phosphide
substrate for LEDs What means novel ? Using
a sophisticated vertical gradient freeze (VGF)
method for growth of GaP single crystals, aiming
at developing GaP substrate with small quantity
of structural defects. Expected Results An
innovative high homogeneity and low defect
density GaP which will be characteristic by (a)
100 - 1000 times lower number of structural
defects in the substrate comparing with LEC
crystal growth, (b) computer aided production and
(c) lower production costs. 2. Validation of
substrate parameter (a) development of new LED
structure utilizing properties of VGF GaP
substrate, (b) production of LED prototypes.
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Project IST-2001-32793 1. Mar.2002 -
31.Aug.2004 New GaP grown by VGF for Light
Emitting Diodes - 9 -
GRAPHICAL PRESENTATION OF PROJECT COMPONENTS WP8
Project Management has general
character and therefore is not
included here.
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Project IST-2001-32793 1. Mar.2002 -
31.Aug.2004 New GaP grown by VGF for Light
Emitting Diodes - 10 -
SYNTHESIS OF POLYCRYSTALLINE MATERIAL PRESENT
STATUS OF WP1 BYPRODUCT POLY InP
Polycrystalline GaP ingot, weight 0,6 kg,
technology level at 1980 - 1990 Equip. PGR 1400,
Metals Research, GB
Polycrystalline InP ingot made by Phostec at Aug.
2002, ingot weight is 9,5 kg. Clearly could be
seen beautiful big grains in the main body and
on the top surface of ingot, which means good
quality and speed of crystallization process in
relevant parts of ingot .
Polycrystalline InP ingot made by Phostec at Nov.
2001, weight 0,7 kg
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Project IST-2001-32793 1. Mar.2002 -
31.Aug.2004 New GaP grown by VGF for Light
Emitting Diodes - 11 -
Application of GaP substrates for MOVPE growth of
LED structures Present status of WP4, WP5, WP6
TECHNICAL BASE BUILDING UP

• Green luminescence is interesting
• Lattice constant ao 5.6 A,
• Eg 2.2 eV
• AlInGaP quaternary lattice matching !
• due strain compensated system
• of thin buffer layers,
• - continuously changed ao

• Deposition of ternary GaP(N)/GaP structure
• GaP1-yNy as new material for LEDs in visible
  spectral range
• Crossover from indirect to direct material
  theoretically predicted
• Strong decrease of band-gap energy with nitrogen
  concentration

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Project IST-2001-32793 1. Mar.2002 -
31.Aug.2004 New GaP grown by VGF for Light
Emitting Diodes - 12 -

• CONCLUSION
• 1. SCIENTIFIC PROJECT WORKSHOP in February /
  March 2003
• In order
• (a) to get a broader base of technical
  achievements , and
• (b) to raise awareness about project and to
  inform EU scientific and industrial community
  acting on field of optoelectronics about project
  intermediate results, and
• (c) to prepare a way for the implementation of
  the project results through EU,
• the partners have agreed to organise a scientific
  project workshop in
• February / March 2003. Attendees should be
• obligatory all partners of project consortium
• invited guests from EUNAS LED community.
• 2. SUPPORT
• Development of new lighting sources open the
  possibilities that new players regardless origin
  are allowed to enter the market. It could be not
  only the companies from EU countries, but maybe
  also from NAS Slovakia, Romania, , which could
  bring new ideas and to foster the competition.
• We strongly encourage everybody and give him
  maximum support, who will have the interest to
  take part in the research and application of new
  lighting sources based on VGF GaP substrates or
  VGF GaP based LEDs.

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Project IST-2001-32793 1. Mar.2002 -
31.Aug.2004 New GaP grown by VGF for Light
Emitting Diodes - 13 -
Consortium and Dates

• Partners
• PHOSTEC LTD., arnovica (Slovakia)
• Slovak Academy of Sciences, Bratislava (Slovakia)
• Slovak University of Technology, Bratislava
  (Slovakia)
• CiS Institut fuer Mikrosensorik gGmbH (Germany)
• Project Start 1st March 2002 Duration 30
  Months
• Overall and financial Coordinator Contact
  Details
• Dietmar Starke, CiS Institut fuer Mikrosensorik
  gGmbHKonrad-Zuse-Straße 14, D-99099 Erfurt
  (Germany)Phone [phone] Fax 49 361
  663 1413 Email dstarke_at_cismst.de
• Scientific Coordinator
• Jozef Matuka, Email phostec_at_bb.psg.sk