Resonant Raman scattering by N-related local modes in AlGaAs/InGaAsN multiquantum wells

We report resonant Raman scattering and secondary ion mass spectrometry measurements on InGaAsN/AlGaAs multiquantum wells grown by plasma-assisted molecular beam epitaxy. The appearance of a strong TO band at resonance with nitrogen (N)-related electronic levels has been observed. The N-induced vibration mode at 470 cm−1 changes in intensity and shape with increasing N and In content. A new vibration mode has been observed at 320 cm−1, whose intensity scales with the N concentration. This mode is not present in InGaAsN films, so it is linked to the presence of Al. Its frequency is close to the B1 silent mode of wurtzite GaN. It is attributed to the formation of GaN pairs, near the MQW interfaces as a consequence of the preferential Al–N bonding.