Optical properties of InGaNAs/GaAs quantum well structures with GaNAs strain relief buffer layers

The modulated optical responses of InGaNAs/GaAs quantum well structures were characterized by photoreflectance spectroscopy. The quantum well excitonic interband transitions were observed in the spectral range above hν=E_g (InGaNAs). When the InGaNAs well is sandwiched in between GaNAs strain relief buffer layers, the quantum confinement potential becomes one step wider and increases the number of quantum states in the system. The quantum well subband energies and wave functions were calculated numerically to compare with the major optical features. The modulated optical responses are enhanced, especially for those quantum states with wave function extending into GaNAs and GaAs barriers where interface space charges induce strong internal field and enhance the electro-modulation efficiency.