Abstract
Optical properties of InGaN/GaN light-emitting diode (LED) samples prepared on the (1122) surface of bulk GaN were investigated. Four samples were prepared with increasing indium concentrations. The LEDs emitted at 527, 531, 556, and 568 nm at 20 mA dc. Their optical polarization ratios were measured and the samples with higher In showed a higher ratio than the shorter wavelength ones. A polarization ratio of 0.65 was measured for the longest wavelength sample. This suggests that the more In incorporated into the quantum well layers leads to an increase in the splitting of the valence subband levels.