Berlin 2008 – wissenschaftliches Programm
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DS: Fachverband Dünne Schichten
DS 8: Semiconductor Nanophotonics: Materials, Models, Devices - GaN based Photonics I: Polaritzation Fields
DS 8.1: Hauptvortrag
Montag, 25. Februar 2008, 14:00–14:45, H 2032
High Efficiency Nonpolar InGaN/GaN based Blue Light Emitting Diodes and Laser Diodes — •Steven P. DenBaars, Mathew C. Schmidt, Robert Farrell, Daniel Fezzell, Stacia Keller, James S. Speck, and Shuji Nakamura — Electrical and Computer Engineering and Materials Departments,University of California, Santa Barbara, California 93106, USA.
We report on the recent advances in the performance of nonpolar InGaN/GaN based blue light-emitting diodes (LEDs) grown on nonpolar a-plane and m-plane GaN. Significant improvement in the outputpower has been achieved by optimizing the growth conditions of the active region. Growth of nonpolar III-nitride based materials have attracted great attention in the recent years because of *polarization-free* heterostructures and the potential of improving the performance of (Al, Ga, In) N-based optoelectronic devices. However the poor structural quality of the planar a-plane and m-plane GaN templates limits the performance of the LEDs grown on them. In this work, we have studied thecontinuous wave (cw) and pulsed current performance of nonpolar InGaN/GaN LEDs and laser diodes grown on reduced defect bulk GaN.
High power and high efficiency nonpolar m-plane nitride light emitting diodes (LEDs) have been fabricated on low extended defect bulk m-plane GaN substrates. The LEDs were grown by metal organic chemical vapor deposition (MOCVD) using conditions similar to that of c-plane device growth. The output power and external quantum efficiency (EQE) of the packaged 300 - 300 mm2 was 23.7 mW and 38.9%, respectively, at 20 mA. The peak wavelength was 407 nm and < 1 nm redshift was observed with change in drive current from 1* 20 mA. The EQE shows a minimal drop off at higher currents.
Recently we have employed these nonpolar (m-plane) InGaN/GaN quantum structures into laser diodes without any Al-containing waveguide cladding layers. These devices utilize thick InGaN quantum wells to generate transverse optical mode confinement and can be grown and fabricated in a manner analogous to InGaN/GaN light emitting diodes. Pulsed and CW lasing operation was demonstrated,with threshold current densities of 3.7 kA/cm2 and 4.3 kA/cm2, respectively.
This work was supported by the Solid State Lighting and Display Center (SSLDC) at the University of California Santa Barbara.