Relationship between threading dislocations and the optical properties in GaN-based LEDs on Si Substrates

Abstract

Owing to the large lattice mismatch between Si and Al(Ga)N, GaN-based structures grown on Si(111) substrates usually have a high density of threading dislocations, which act as non-radiative recombination centers. In this work, we analyze the relationship between threading dislocations and the internal quantum efficiency of GaN-based light-emitting diodes (LEDs) by using various characterization methods such as atomic force microscopy, transmission electron microscopy, cathodoluminescence, photoluminescence, and electroluminescence measurements. Non-radiative recombination centers are found to have a direct effect on the optical properties of optoelectronics devices such as LEDs. Reducing the density of the threading dislocations is demonstrated to be a key parameter in improving the output power of LEDs grown on Si substrates.