Characteristics of Micro‐Size Light‐Emitting Diode for Illumination and Visible Light Communication

The white light‐emitting diode (LED) modules, in which the GaN‐based blue‐LED chip with 4 × 4 arrayed pixels are packaged with chip‐on‐board technique and welded on a print circuit board, are fabricated for both illumination and visible light communication (VLC). The effects of the mesa size on the characteristic features are explored. It shows that the pixels with small size can sustain high saturated current density. Under the saturated current density, the highest luminous flux of 278.4 lm can be obtained by using the largest pixel of 160 µm‐diameter, or the highest 3‐dB modulation bandwidth of 127.3 MHz can be obtained by using the smallest pixels of 60 µm‐diameter. In case the white‐LED module works for a long time, the injected current density should be far away from the saturated current density. On condition that the 3‐dB modulation bandwidth of 100 MHz is required, the white‐LED module with 100 µm‐diameter pixels is proposed and the luminous flux can reach 164.8 lm. Subsequently, the electrode size is optimized to get higher luminous flux. By enlarging the p‐electrode, the white‐LED module with 120 µm‐diameter pixels can achieve the luminous flux of 235.2 lm while the 3‐dB modulation bandwidth holds 100 MHz. The GaN‐based blue‐light‐emitting diodes (LED) chips with 4 × 4 arrayed pixels are fabricated and packaged by chip‐on‐board technique and welded on printed circuit board as white‐LED modules. The size of the mesa and the electrodes are carefully selected to get a compromise between the luminous flux and the modulation bandwidth for the dual function of illumination and communication.