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Optimization of InGaN/(In,Al,Ga)N based near UV-LEDs by MQW strain balancing with in-situ wafer bow sensor
A. Knauer1, T. Kolbe2, S. Einfeldt1, M. Weyers1, M. Kneissl1,2, and T. Zettler3
1 Ferdinand-Braun-Institut für Höchstfrequenztechnik, Gustav-Kirchhoff-Strasse 4, 12489 Berlin, Germany
2 Technische Universität Berlin, Institut für Festkörperphysik, Hardenbergstr. 36, 10623 Berlin, Germany
3 LayTec GmbH, Helmholtzstr. 13-14, 10587 Berlin, Germany
Published in:
phys. stat. sol. (a), vol. 206, no. 2, pp. 211-214 (2009).
© 2009 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim. Personal use of this material is permitted. However, permission to reprint/republish this material for
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Abstract:
A high resolution curvature sensor was used for in-situ monitoring
of the strain state during the growth of the InGaN multiple-
quantum-well (MQW) for near UV light emitting diodes
(LEDs). The LED heterostructures were grown by metalorganic
vapor phase epitaxy. LEDs containing different
InxAl0.16Ga0.84-xN barrier layers were compared. The results
were correlated with the external quantum efficiency (EQE)
and the current induced shift of the emission wavelength of
the LEDs. It was found that strain-compensated or slightly
compressively strained InxAl0.16Ga0.84-xN barrier layers in the
MQW, for which the net polarization in the InGaN quantum
wells is close to zero, result in the highest EQE and in a stable
emission wavelength independent of the drive current.
PACS:
78.60.Fi, 81.05.Ea, 81.07.St, 81.70.Fy, 85.60.Bt, 85.60.Jb
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