Bereiche | Tage | Auswahl | Suche | Aktualisierungen | Downloads | Hilfe

HL: Fachverband Halbleiterphysik

HL 85: Poster Session II

HL 85.123: Poster

Donnerstag, 17. März 2011, 18:00–21:00, P4

Internal quantum efficiency of high In content GaInN quantum well structures — •Fedor Alexej Ketzer, Holger Jönen, Heiko Bremers, Uwe Rossow, and Andreas Hangleiter — Institute of Applied Physics, TU Braunschweig, Germany

The internal quantum efficiency (IQE) of GaN based light emitters shows a strong reduction for emission wavelenghts beyond 500 nm. In order to get LEDs and LDs emitting in the green spectral region the indium content has to be increased. This leads to stronger piezoelectric fields in the quantum wells resulting in a reduced oscillator strength. In addition the low growth temperatures needed for high In contents and the larger strain may lead to an increased defect density and stronger nonradiative recombination. In this contribution we analyze the internal quantum efficiency of GaInN quantum well structures measured by temperature and excitation power dependent photoluminescence. The samples were grown by MOVPE on sapphire or bulk GaN substrates. We investigated single and multiple quantum well structures with indium contents between 18% and 32% and quantum well thickness between 0.8 nm and 2.0 nm. For structures emitting at similar wavelengths the IQE can be optimized using thin quantum wells and high indium contents. Furthermore we studied the influence of subsequent layers on the optical properties of the QWs. The thickness and the growth rate of the GaN barrier directly following the QW turned out to be key parameters for improving the efficiency of our structures.