Red-green-blue (RGB) full-color micro light-emitting diodes (μ-LEDs) fabricated from semipolar (20-21) wafers, with a quantum-dot photoresist color-conversion layer, were demonstrated. The semipolar (20-21) InGaN/GaN μ-LEDs were fabricated on large (4 in.) patterned sapphire substrates by orientation-controlled epitaxy. The semipolar μ-LEDs showed a 3.2 nm peak wavelength shift and a 14.7% efficiency droop under
200
A
/
cm
2
injected current density, indicating significant amelioration of the quantum-confined Stark effect. Because of the semipolar μ-LEDs’ emission-wavelength stability, the RGB pixel showed little color shift with current density and achieved a wide color gamut (114.4% NTSC space and 85.4% Rec. 2020).
The
light-emitting diode (LED) is among promising candidates of
light sources in visible light communication (VLC); however, strong
internal polarization fields in common c-plane LEDs,
especially green LEDs, result in low frequency and limited transmission
performance. This study aims to overcome the limited 3-dB bandwidth
of long-wavelength InGaN/GaN LEDs. Thus, semipolar (20–21)
micro-LEDs (μLEDs) were fabricated through several improved
approaches on epitaxy and chip processes. The μLED exhibits
a 525 nm peak wavelength and good polarization performance. The highest
3-dB bandwidth up to 756 MHz and 1.5 Gbit/s data rate was achieved
under a current density of 2.0 kA/cm2. These results suggest
a good transmission capacity of green semipolar (20–21) μLEDs
in VLC applications.
We propose and implement a high-bandwidth white-light visible light communication (VLC) system accomplishing data rate of 2.805 Gbit/s utilizing a semipolar blue micro-LED. The system uses an InGaN/GaN semipolar (20-21) blue micro-LED to excite yellow phosphor film for high-speed VLC. The packaged 30 μm 2 × 4 blue micro-LED array has an electrical-to-optical (EO) bandwidth of 1042.5 MHz and a peak wavelength of 447 nm. The EO bandwidth of the white-light VLC system is 849 MHz. Bit error rate (BER) of 2.709 × 10−3 meeting the pre-forward error correction (FEC) threshold is accomplished by employing a bit and power loaded orthogonal frequency division multiplexing (OFDM) signal. The proposed white-light VLC system employs simple and inexpensive yellow phosphor film for white-light conversion, complex color conversion material is not needed. Besides, no optical blue filter is employed in the white-light VLC system. The fabrication of the InGaN/GaN semipolar (20-21) blue micro-LED is discussed, and its characteristics are also evaluated.
We propose a flexible white-light system for high-speed visible-light communication (VLC) applications, which consists of a semipolar blue InGaN/GaN single-quantum-well micro-light-emitting diode (LED) on a flexible substrate pumping green
CsPbBr
3
perovskite quantum-dot (PQD) paper in nanostructure form and red CdSe QD paper. The highest bandwidth for
CsPbBr
3
PQD paper, 229 MHz, is achieved with a blue micro-LED pumping source and a high data transmission rate of 400 Mbps; this is very promising for VLC application. An 817 MHz maximum bandwidth and a 1.5 Gbps transmission speed are attained by the proposed semipolar blue micro-LEDs. The proposed flexible white light system and the high-bandwidth PQD paper could pave the way for VLC wearable devices.
A record 4.343 Gbit/s green color micro-light-emitting-diode (μ-LED) based visible-light-communication (VLC) is demonstrated. We designed and fabricated the InGaN/GaN μ-LED array with modulation bandwidth > 1.1 GHz. The micro-LED was grown on semipolar (20-21) orientation, which could offer higher modulation bandwidth at a lower current density.
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