Effect of the InGaN/GaN Superlattice Thickness on Structures and Luminescence Performances of GaN-Based Yellow LED Grown on Patterned Sapphire Substrate

The InGaN/GaN multi-quantum well LEDs were grown on the patterned sapphire substrate by metal organic chemical vapor deposition. Two sets of InGaN/GaN superlattices with periods of 10 and 20 were inserted under the quantum well. SEM, HRXRD, and SIMS tests show that the increase of InGaN/GaN superlattice thickness more effectively releases the stress of the quantum well, and increases the density and size of V-shaped pits in the quantum well, as well as the indium phase segregation in the quantum well. It is found that the peak wavelength and half-height width increase with the increase of superlattice thickness, which is related to the strengthening of the “local state effect” in the wells. The luminous intensity of photoluminescence spectrum for two LED samples shows that the luminous intensity increases slightly with the increase of superlattice thickness, which is related to the density and size of V-shaped pits, as well as the transport path and injection intensity of holes. However, the optimal value of the superlattice thickness remains to be studied in the future.