Enhancement of Modulation Bandwidth for VLC Utilizing Green Mini‐LED Light Source

ABSTRACT This paper presents a comprehensive investigation of three different sizes of green mini–light‐emitting diodes (Mini‐LEDs) as light sources for visible light communication (VLC) systems, focusing on the key factors affecting their modulation bandwidth. Atomic layer deposition (ALD) is employed to optimize device performance by mitigating sidewall defects induced by dry etching during fabrication. The effectiveness of ALD sidewall passivation is experimentally validated through significant improvements in modulation bandwidth across all device sizes. Specifically, the 50 × 80 µm 2 Mini‐LED exhibits an increase in bandwidth from 74.1 to 90.1 MHz, corresponding to a 21.6% enhancement. Similarly, the 80 × 120 µm 2 and 100 × 200 µm 2 Mini‐LEDs demonstrate bandwidth improvements from 57.9 to 66.4 MHz (14.7%) and from 35.1 to 40.2 MHz (14.5%), respectively. These results confirm that ALD sidewall repair effectively suppresses nonradiative recombination, thereby enhancing the high‐frequency modulation characteristics of green Mini‐LEDs for VLC applications. These findings also provide valuable guidance for the design of future VLC systems, suggesting that device miniaturization combined with optimized sidewall passivation can enable higher data rates and more compact, energy‐efficient optical transmitters. For instance, the observed bandwidth enhancements could directly translate into proportional increases in achievable data rates, enabling VLC links to support faster information transfer in high‐speed indoor or vehicular communication scenarios.