Comparison of InxGa1-xN/GaN MQWs grown on GaN and sapphire substrates

In-x Ga1-xN/GaN multi quantum wells were grown on GaN and sapphire substrates by using metal-organic chemical-vapor deposition. A detailed analysis of the satellite peaks observed in the high-resolution X-ray diffraction patterns showed the presence of more compressive strain in In-x Ga1-xN/GaN MQWs grown on GaN substrates than in the MQWs grown on sapphire substrates. However, the optical investigations of the InxGa1-xN/GaN MQWs grown on GaN, showed a lower Stokes-like shift in photoluminescence than the same MQWs grown on sapphire did. The Stokes-like shift observed for MQWs is attributed to a potential fluctuation and the quantum confined Stark effect induced by the built-in internal field due to spontaneous and strain-induced piezoelectric polarizations.