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 B-1 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. (c) 2006 Elsevier B.V. All rights reserved.