Polarization field effects on the recombination dynamics in low In-content InGaN multi-quantum wells

The interplay of polarization fields and free carrier screening in InxGa1-xN/GaN (0.03 < x < 0.07) multiple quantum wells is studied by combining photoluminescence (time-integrated and time-resolved) and cathodoluminescence studies, in an excitation density range from 108 to 1012 cm(-2) of generated e-h pairs. For such low In content, the quantum-confined Stark effect is verified to rule the recombination dynamics, while effects of carrier localization in potential fluctuations have a minor role. Efficient field screening is demonstrated in CL steady-state high-injection conditions and in PL time-resolved experiments at the maximum excitation density. Under recovered nearly flat band conditions, quantum confinement effects are revealed and a high and possibly composition-dependent bowing parameter is extrapolated. Information on radiative and non-radiative rates for carrier recombination in the wells is obtained, both from steady-state and from time-resolved experiments, modelling the carrier dynamics in the framework of a theoretical rate equation model, which calculates electronic states and recombination rates in the nanostructure by coupling complete self-consistent solutions of Schr6dinger and Poisson equations.