Investigation of Modulation Bandwidth of InGaN Green Micro-LEDs by Varying Quantum Barrier Thickness

InGaN-based micro light-emitting diodes (micro-LEDs) with 5, 10, and 13 nm quantum barrier (QB) thickness were fabricated by metal-organic chemical vapor deposition (MOCVD) to investigate the influence of quantum-confined Stark effect (QCSE) on modulation bandwidth and luminous performance of devices. The room-temperature photoluminescence (PL), low-temperature time-resolved PL (TRPL), and electroluminescence (EL) results show that the decrease of QB thickness is beneficial to reduce QCSE of the device. The thinner QB thickness is good for improving the modulation bandwidth because the thinner QB is more beneficial to increase the total carrier recombination rate, but it is not conducive to the improvement of external quantum efficiency (EQE) due to degraded crystal quality. In addition, the modulation bandwidth of the device was calculated by using ABC model in combination with simulation. The calculation is in good agreement with the measured value. What is more, an optical link using an orthogonal-frequency division multiplexing (OFDM) modulation scheme was demonstrated. The transmission data rate increases with the increase of QB thickness from 1.309 to 1.773 Gbps, even though the modulation bandwidth decreases from 245 to 169 MHz. This work provides a way to balance the quantum efficiency and communication performance of green micro-LEDs.