Electro-modulation enhancement in the InGaNAs/GaAs quantum well structures

Electrooptical properties of InGaNAs/GaAs quantum well structures were investigated by photoreflectance spectroscopy. The MBE grown structures consist of a central InGa-NAs well, GaAs barriers, and GaAsN strain compensating buffer layers of different thickness. More quantum states and extended wave functions in the system with strain relief GaAsN barriers due to broader and lower confinement profile. Particular electro-modulated spectral features corresponding to excitonic interband transitions are enhanced. Compared with the numerically calculated quantum state energies and wave functions, the electromodulation enhanced transitions were those involving quantum states with wave functions distribute in wider regions and extend more from the InGaNAs well into the space charge region near interfaces. It was the internal electric field near the heterointerfaces strongly enhanced the electro-modulation efficiency.