Modulated Epitaxial Lateral Overgrowth of AlN for Efficient UV LEDs
IEEE Photonics Technol. Lett., vol. 24 , no. 18, pp. 1603-1605 (2012).
© Copyright 2012 IEEE - All Rights Reserved. Personal use of this material is permitted. However, permission to reprint/republish this material for advertising or promotional purposes or for creating new collective works for resale or redistribution to servers or lists, or to reuse any copyrighted component of this work in other works must be obtained from the IEEE.
A reduction of the threading dislocation density in AlN layers on a sapphire from 1010 cm-2 to 109 cm-2 was achieved by applying epitaxial lateral overgrowth (ELO) of patterned AlN and sapphire templates. By varying the growth temperature, it is possible to influence the lateral growth rate and modulate the thickness before coalescence. With a two-step growth at two different temperatures, up to 11-µm thick crackfree layers were achieved. Using these ELO AlN templates, the light emitting diode (LED) output power was >1 mW dc at 295 nm and ≈ 4mW at 324 nm which is a significant increase compared to planar templates. The usefulness of modulated ELO AlN templates for ultraviolet LEDs has thus been validated.
1 Ferdinand-Braun-Institut, Leibniz-Institut für Höchstfrequenztechnik, Gustav-Kirchhoff-Straße 4, D-12489 Berlin, Germany
2 Institute of Solid State Physics, Technische Universität Berlin, Berlin 10623, Germany
3 Palo Alto Research Center, Palo Alto, CA 94304 USA
Epitaxial growth, epitaxial layers, light emitting diodes (LEDs), semiconductor materials.