Abstract
Nonpolar m-plane InGaN/GaN light emitting diode structures with quantum well (QW) were grown on LiAlO2 (100) substrates. Their photoluminescence and electroluminescence were investigated at different excitation levels. It was shown that in QW of InGaN with the pronounced InGaN band tailing, the populating of both the first and the second valence subbands of InGaN takes place due to tunneling of charge carriers and, therefore, a lower degree of polarization of the electroluminescence was observed in comparison with photoluminescence. The differences in luminescence properties under optical and electrical excitation are discussed.