Strong modification of spontaneous emission rate in nanorod light-emitting diode structures

This study investigates the characteristics of modifications in spontaneous emission (SE) from GaN-based nanorod light-emitting diode (LED) structures using the three-dimensional finite-difference time-domain method. The simulated nanorod LED structure is assumed to be enclosed by perfect conductors and includes InGaN multiple-quantum-well active layers emitting at 500 nm. In the simulation, the modification of the SE rate is calculated as the structural parameters of nanorods are varied. The SE rate is found to depend strongly on the radius of nanorods. Large enhancement of the SE rate is observed when the resonant modes are formed inside the nanorod cavity. For both the transverse-electric and transverse-magnetic modes, the SE rate of nanorod LED structures can be enhanced by more than six times when the radius or height of the nanorod is optimally chosen. This large increase in the SE rate can lead to considerable increase in the internal quantum efficiency of LEDs, making nanorod structures prime candidates for future high-efficiency LEDs than can overcome the efficiency limit of current LED structures.