Comparative study of polar and semipolar (1122) InGaN layers grown by metalorganic vapour phase epitaxy

InGaN layers were grown simultaneously on (1122) GaN and (0001) GaN templates by metalorganic vapour phase epitaxy. At higher growth temperature (≥750°C), the indium content (<15%) of the (1122) and (0001) InGaN layers was similar. However, for temperatures less than 750°C, the indium content of the (1122) InGaN layers (15%-26%) were generally lower than those with (0001) orientation (15%-32%). The compositional deviation was attributed to the different strain relaxations between the (1122) and (0001) InGaN layers. Room temperature photoluminescence measurements of the (1122) InGaN layers showed an emission wavelength that shifts gradually from 380 nm to 580 nm with decreasing growth temperature (or increasing indium composition). The peak emission wavelength of the (1122) InGaN layers with an indium content of more than 10% blue-shifted a constant value of ≈(50-60) nm when using higher excitation power densities. This blue-shift was attributed to band filling effects in the layers.