Structural Optimization of High-Power AlGaInP Resonant Cavity Light-Emitting Diodes for Visible Light Communications

For developing high-power resonant cavity light-emitting diodes (RCLEDs) appropriate for visible light communications, we have investigated the effect of reflectivity of a p-side distributed Bragg reflector (p-DBR) and the number of quantum wells (QWs) in active layers on the spectral characteristics and optical power of RCLEDs. As the reflectivity of p-DBR increased. the full width at half maximum (FWHM) of the electroluminescence (EL) spectrum was reduced from 12.3 to 3.6 nm, whereas the relative integrated intensity decreased from 1.0 to 0.37, which can be attributed to the improvement of spectral purity of peaks with in-phase condition. As the number of QWs decreased, optical power increased owing to the reduction of the optical loss of recycling light in the active region. Using the optimized structural conditions, we demonstrated RCLEDs having a modulation speed up to 130 MHz in free space, which shows that the optimized RCLED structure is a promising candidate for visible light communications (VLCs).