Electroluminescence Characterization of (2021) InGaN/GaN Light Emitting Diodes with Various Wavelengths

The optical characteristics of InGaN/GaN light emitting diodes (LEDs) grown on (2021) bulk GaN substrates with wavelengths 469, 487, 510, and 528 nm were investigated. From 2 to 100 mA, the peak emission wavelength for green LEDs blue-shifted by 6.2 nm. Emission spectra widths were almost independent of the injection current. These results suggest that (2021) LEDs have a smaller polarization field and smaller indium fluctuations in the quantum wells. Optical polarization ratios for the LEDs varied between 0.4 and 0.5, which are larger than reported values. A weak dependence of the polarization ratio on the indium composition was observed.