Impact of Crystal Orientation on Modulation Bandwidth: Towards GaN LED-Based High-Speed Visible Light Communication

Abstract

Light-emitting diodes (LEDs) with high modulation bandwidth are required for high-speed visible light communication applications. Crystal orientation in the GaN LED structure plays a key factor in its modulation bandwidth as the recombination lifetime is highly dependent on crystal orientation owing to the Quantum-Confined Stark Effect (QCSE). In this study, six different crystal orientation multi-quantum well (MQW) GaN LEDs are simulated to understand the impact of heterostructure orientation on modulation bandwidth, radiative recombination rates, and emission intensity. The results of this study demonstrate that semi-polar 101¯3¯ MQW LEDs provide the highest bandwidth in the current density range of 9–20 kA/cm2 compared to the other five orientations. For instance, the semi-polar 101¯3¯-based LED offers a modulation bandwidth of 912.7 MHz at 20 kA/cm2 current density. These results suggest that the semi-polar 101¯3¯ orientation-based LED has the potential to support a high-speed visible light communication system.

Keywords

• GaN LED
• modulation bandwidth
• visible light communications
• crystal orientation