REFLECTOR LAYERS - DBRs & HYBRIDS Reflector layers that shine out in LED production • Sputter processes for sensitive substrates and sub layers • Reflectivities close to 100% Relative to the metallic reflectors, so-called hybrids (metal/ dielectric combinations) and Distributed Bragg Relectors “DBRs” (full dielectric stacks) offer near 100% reflectivity, improving device extraction efficiency and light output according to type of LED design. Evatec’s cathode technology on the Radiance platform allow dielectric stacks with the widest reflection band to be deposited accurately and repeatibly. Plasma Emission Monitoring for enhanced layer stoichiometry control and in situ broadband monitoring for precise layer end point termination enable tight process control for film designs with large numbers of layers requiring the greatest accuracy. The Radiance system and process geometry also protects damage and temperature sensitive substrate materials and helps thin film engineers to develop new device designs and materials for the next generation LEDs. Evatec’s hybrid and DBR stack solutions are tailored in cooperation with customers according to: - Substrate material - Wavelength range - Device geometry, angular range - Device packaging
Photo courtesy of OSRAM
REFLECTOR LAYERS - DBRs & HYBRIDS
Typical Dielectric Stack Materials Material
Refractive Index @500 nm
Transmission range [nm]
TiO2
2.40
400 - 12000
Nb2O5
2.35
380 - 7000
Ta2O5
2.1
350 - 7000
HfO2
1.90
230 - 7000
Al2O3
1.63
200 - 5000
SiO2
1.46
200 - 2000
MgF2
1.38
150 - 7000
Optical performance for typical DBR Mirror Stack design 25 layers SiO2 / Nb2O5 on Sapphire substrate
Optical performance for typical Hybrid Mirror Stack design 13 layers Al / Nb2O5 / SiO2
Evatec Ltd. Lochrietstrasse 14 CH-8890 Flums Switzerland Tel: + 41 81 720 1080 Fax: + 41 81 720 1081 info@evatecnet.com www.evatecnet.com Product descriptions, photos and data are supplied within the brochure for general information only and may be superseded by any data contained within Evatec quotations, manuals or specifications.