Light-polarization characteristics of electroluminescence from InGaN/GaN light-emitting diodes prepared on (1122)-plane GaN

Light polarization and emission spectra from InGaN/GaN quantum-well light-emitting diodes (LEDs) were investigated. The LEDs were prepared on the (1122) plane of wurtzite GaN. Polarization and spectrum measurement was performed at different observation angles with respect to the LED surface. Partially polarized electroluminescence was confirmed at any angle of observation, where the emission intensity tended to be greater when a polarizer was aligned along the c axis of the InGaN/GaN LED structure. The results clearly indicated the inclination of the c axis relative to the LED surface. As a result, two light polarizations were identified and they were assigned to two different electronic transitions in relation to emission peak energies. Possible alteration of the valence-band structure was suggested due to the induced strain.