Influence of Current Density and Capacitance on the Bandwidth of VLC LED

Visible light communication devices have attracted significant attention recently due to their advantageously high transmission rates. It has been shown that current density and device capacitance has a significant effect on the frequency of visible-light GaN communication devices. We demonstrate a similar linear relationship in a micro-light emitting device (LED) between the -3 dB response frequency, current density, and device diffusion capacity. An experiment was conducted in which, when the device's single light-emitting unit size is between 60-120 μm, increasing the LED current density, the lifetime of the device is substantially reduced for the period of the device's light emission process, and reducing device capacitance improved the device response frequency. To show the relationship between device capacitance and response frequency, four groups of devices with a single unit of the visible GaN communication device was reduced from 120 to 60 μm, the current was set to 35 mA, and the matrix of devices was increased from 1 × 1 to 4 × 4, generally, as the number of series increases, the capacitance decreases. As a result, the -3 dB device response frequency increased from 18 to 74 MHz and luminous efficiency increased from 37 to 74 lm/W, the linear relationship between capacitance and response frequency has been confirmed.