Optical spectroscopic study of electric field sharing effects in piezoelectric GaN/Al0.65Ga0.35N multi-quantum well structures

We have studied a series of GaN/Al0.65Ga0.35N samples of varying well and barrier widths by cathodoluminescence and photoluminescence spectroscopy. These samples consist of unstrained GaN quantum wells and strained Al0.65Ga0.35N barriers. Some of the samples exhibit micro-cracks on their surface around which the barriers are partially relaxed and the quantum wells strained. The observation of the quantum well emission under two different strain conditions allows the relative effects of spontaneous polarization and piezoelectric polarization on the emission energies to be compared. We are able to accurately model the emission energies for both strain configurations if we consider the large electric fields present within the quantum wells to be due almost entirely to piezoelectric and field sharing effects.