a1 Department of Physics, University of North Texas, Denton, Texas 76203
a2 Argonne National Laboratory, Center for Nanoscale Materials, Argonne, Illinois 60439
a3 SUPA, Institute of Photonics, University of Strathclyde, Glasgow, UK
a4 CICECO, Universidade de Aveiro, 3810-193 Aveiro, Portugal
a5 Department of Physics, University of North Texas, Denton, Texas 76203
Ultrafast differential transmission spectroscopy was employed to study the carrier dynamics in InGaN/GaN multiple quantum wells with high inverted hexagonal pits density due to threading dislocation. By monitoring the temporal evolution of the excitonic absorption spectrum, a reduction of the quantum-confinement Stark shift was observed due to the photo-induced in-well field screening at low carrier densities and excitonic absorption quenching at high carrier densities. By comparing the differential absorption spectra at various injected carrier densities, the in-well field screening effect was distinguished from excitonic bleaching.
(Received March 06 2012)
(Accepted May 22 2012)