Dresden 2009 – wissenschaftliches Programm

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HL: Fachverband Halbleiterphysik

HL 27: GaN: preparation and characterization I

HL 27.9: Vortrag

Mittwoch, 25. März 2009, 12:00–12:15, BEY 81

Radiative recombination in GaInN quantum wells investigated via time-resolved photoluminescence — •Torsten Langer, Holger Jönen, Carsten Netzel, Uwe Rossow, and Andreas Hangleiter — Institute of Applied Physics, TU Braunschweig

The optical properties of group-III-nitrides are strongly influenced by an interplay between radiative and nonradiative recombination processes. For our high internal efficiency c-plane GaInN/GaN quantum wells, the effective lifetime, determined by time-resolved photoluminescence(PL)-spectroscopy, is dominated by radiative recombination nearly up to room temperature. This is evidenced by an increase of the effective lifetime with increasing temperature, which is tantamount to a high internal quantum efficiency, proving the results from temperature and excitation power dependent PL-measurements (continuous wave excitation). While radiative lifetime increases almost linearly at higher temperatures, the nonradiative lifetime drops due to thermal activation of nonradiative processes. The influence of excitons is clearly visible too, when fitting the intensity transients with a model based on radiative excitonic and nonradiative recombination. In this model, the ratio between excitons and free carriers are described by the law of mass action. Furthermore, we observe higher effective lifetimes with increasing quantum well thickness, due to a decreased oscillator strength caused by piezoelectric fields. In m-plane GaInN quantum wells, the interplay between radiative and nonradiative recombination processes is present as well. Here we observe a higher oscillator strength and therefore a shorter effective lifetime.