Si-substrate vertical-structure InGaN/GaN micro-LED-based photodetector for beyond 10 Gbps visible light communication

Visible light communication (VLC) has emerged as a promising communication method in 6G. However, the development of receiving devices is much slower than that of transmitting devices, limited by materials, structures, and fabrication. In this paper, we propose and fabricate an InGaN/GaN multiple-quantum-well-based vertical-structure micro-LED-based photodetector (mu PD) on a Si substrate. A comprehensive comparison of the photoelectrical performance and communication performance of three sizes of mu PDs, 10, 50, and 100 mu m, is presented. The peak responsivity of all three mu PDs is achieved at 400 nm, while the passband full-widths at half maxima are 87, 72, and 78 nm for 10, 50, and 100 mu m mu PDs, respectively. The -20 dB cutoff bandwidth is up to 822 MHz for 50 mu m mu PD. A data rate of 10.14 Gbps is experimentally demonstrated by bit and power loading discrete multi-tone modulation and the proposed digital pre-equalizer algorithm over 1 m free space utilizing the self-designed 4 x 4 50 mu m mu PD array as a receiver and a 450 nm laser diode as a transmitter. This is the first time a more than 10 Gbps VLC system has been achieved utilizing a GaN-based micro-PD, to the best of our knowledge. The investigation fully demonstrates the superiority of Si substrates and vertical structures in InGaN/GaN mu PDs and shows its great potential for high-speed VLC links beyond 10 Gbps. (c) 2022 Chinese Laser Press