Researchers from China's Fudan University, in collaboration with researchers from Peking University, have developed high-performance microLED arrays, on diamond substrates, suitable for optical I/O.
The research combines several enabling technologies, including long-wavelength InGaN epitaxy, three-quantum-well active region design, diamond heterogeneous integration, transfer printing and two-photon fabricated microlenses. This resulted in highly efficient microLEDs, with very low drive currents and excellent energy efficiency. The researchers say that the diamond substrates effectively suppress self-heating, enabling high-speed operation while significantly improving thermal management compared with conventional glass substrates.
The researchers demonstrated yellow and red InGaN microLEDs, optimized through superlattice strain engineering and a three-period quantum well design. The microLEDs were transfer-printed onto diamond, with microlenses fabricated by two-photon lithography for coupling optimization. They reported that the 20 µm yellow micro-LED achieved an electrical-to-optical bandwidth of 2850.4 MHz at 6.25 A/cm², while the 20 µm red device reached 2593.4 MHz at 50 A/cm². With on–off keying (OOK) modulation through a 1 m fiber link, 20 µm and 40 µm yellow devices achieved 1.5 Gbps at 25 µA (6.25 A/cm²) and 50 µA (3.125 A/cm²), with energy efficiencies of 0.056 pJ/bit and 0.110 pJ/bit, respectively.
Following these excellent results, the researchers have established a new company called Nexilumen to commercialize the technology. The company raised 15 million RMB (around $2.2 million USD) in its seed round.
