Wavelength Red-Shift of Long Wavelength InGaN/GaN Multi-Quantum Well by Using an InGaN Underlying Layer

Long-wavelength GaN based light-emitting diodes are of importance in full color displays, monolithic white light-emitting diodes and solid-state lighting, etc. However, their epitaxial growth faces great challenges because high indium ( In) compositions of InGaN are difficult to grow. In order to enhance In incorporation and lengthen the emission wavelength of a InGaN/GaN multi-quantum well (MQW), we insert an InGaN underlying layer underneath the MQW. InGaN/GaN MQWs with various InGaN underlying layers, such as graded In-y Ga1-yN material with linearly increasing In content, or In-y Ga1-yN with fixed In content but different thicknesses, are grown by metal-organic chemical vapor deposition. Experimental results demonstrate the enhancement of In incorporation and the emission wavelength redshift by the insertion of an InGaN underlying layer.