Preparation Of GaN-based Micro-LEDs And Their Visible Light Communication Performance

Visible Light Communication(VLC)technology is a new type of technology that uses visible light sources and detection to achieve high-speed wireless data transmission,complementing existing wireless radio frequency communication technologies to meet the growing demand for high-speed wireless communication services.Visible light communication is the use of high modulation bandwidth LED chips to achieve fast data transmission through high frequency light signals that cannot be perceived by the human eye while considering visible light illumination.The use of gallium nitride-based micron size LEDs(Micro-LEDs)as the light source for VLC systems has been a hot research topic in recent years.This technology has significant advantages such as strong confidentiality,fast data transmission rate,strong antielectromagnetic interference and unlimited spectrum resources,and is very suitable for indoor short-range communication and positioning,indoor Internet communication,etc.It has great market prospects.This paper is based on the study of the effect of size on the performance of MicroLED visible light communication and the design of a device structure with multiple sizes integrated in the same pixel cell.The process flow of the Micro-LED devices is described in detail,using techniques including plasma enhanced chemical deposition(PECVD),photolithography,reactive ion etching(RIE),plasma etching(ICP),electron beam evaporation(PVD)and rapid thermal annealing(RTA).Small-sized GaN-based blue/green Micro-LED chips were prepared using deep UV lithography.During the preparation process,the sidewalls of the devices were repaired by passivation in order to improve the performance of the devices,and finally,Micro-LED chips with good optoelectronic properties were obtained.The optoelectronic properties of the prepared Micro-LED devices were also characterised,including current-voltage(I-V)characteristics,electroluminescence spectra(EL)and the integrating sphere method to characterise the luminance data properties.At the same time,a pioneering visible light communication test platform was built in the group to initially test the modulation bandwidth of the Micro-LED devices,confirming that the process-optimised MicroLEDs have high bandwidth characteristics,with the modulation bandwidth reaching372.6MHz at an injection current density of 5.7k A/cm2 for blue 20?m Micro-LEDs,and 372.6MHz for green The 20?m Micro-LEDs have a modulation bandwidth of176.6MHz at an injection current density of 12.1k A/cm2,confirming their potential as optical transmitters for high-speed visible light communication systems.In addition,to test the communication performance of the system,a preliminary eye diagram test system was built and a simple eye diagram test was completed,laying the foundation for the subsequent work.