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In this work, based on transfer printing technology, planar integration of RGB InGaN‐based micro‐LEDs on flexible transparent material was realized. By measuring the optoelectronic parameters, we demonstrated the feasibility of this integrated device in full‐color display applications. In addition, based on the on‐off keying modulation and wavelength division multiplexing, visible light communication in parallel channels can be achieved. Relevant studies have demonstrated the broad prospects of InGaN‐based micro‐LED devices in multifunctional flexible integrated optoelectronics applications. [ABSTRACT FROM AUTHOR]

Recently, the rapidly developing Internet of Things (IoT) needs to support massive connectivity with high transmission data rate, which requires IoT transmitters with high speed and low power consumption. In this work, non-polar micro-LED operating at low current density of 10 A/cm $^{2}$ can still maintain a high bandwidth of 508 MHz and near-peak external quantum efficiency (EQE), making it promising for low-power, energy-efficient visible light communication (VLC) to address the challenge. At 10 A/cm $^{2}$ , non-polar micro-LEDs can achieve a low power consumption and high energy efficiency, still maintaining the data rate of 0.25 Gbps. In addition, data rates of 2 Gbps and 1.1 Gbps were also successfully achieved for non-polar micro-LED operating at 320 and 50 A/cm $^{2}$ , respectively, to evaluate the relationship between power consumption and achievable data rate. The capability of non-polar micro-LED that can realize low-power consumption and high bandwidth at low current density is expected to play a great role in the field of energy-efficient VLC, multi-function display and IoT in the future. [ABSTRACT FROM AUTHOR]

Red micro light-emitting diodes (micro-LEDs) on silicon substrates are important components for realizing large-scale and low-cost micro-LED displays. Recently, InGaN red micro-LEDs have received enormous attention because their external quantum efficiency (EQE) is not significantly affected by size effect and they are compatible with existing green and blue LED material systems. Here, taking advantage of the easy removal of silicon substrates, we successfully achieved the transfer printing of InGaN red micro-LEDs. By removing the light-absorbing Si substrate and introducing a metal mirror, the transfer printed micro-LEDs exhibited better color purity, higher optical power, and higher EQE. At 0.5 A/cm2, the optical power of micro-LEDs on glass was 300% higher than that of micro-LEDs on silicon. And the peak EQE of transfer printed micro-LEDs was 2.3 times that of micro-LEDs on native substrate. This work is applicable to most transfer printing techniques requiring PDMS stamps, and shows the potential to realize InGaN-based full-color micro-LED displays by mass transfer in the future. [ABSTRACT FROM AUTHOR]

InGaN-based micro light-emitting diodes (micro-LEDs) with 5, 10, and 13 nm quantum barrier (QB) thickness were fabricated by metal-organic chemical vapor deposition (MOCVD) to investigate the influence of quantum-confined Stark effect (QCSE) on modulation bandwidth and luminous performance of devices. The room-temperature photoluminescence (PL), low-temperature time-resolved PL (TRPL), and electroluminescence (EL) results show that the decrease of QB thickness is beneficial to reduce QCSE of the device. The thinner QB thickness is good for improving the modulation bandwidth because the thinner QB is more beneficial to increase the total carrier recombination rate, but it is not conducive to the improvement of external quantum efficiency (EQE) due to degraded crystal quality. In addition, the modulation bandwidth of the device was calculated by using ABC model in combination with simulation. The calculation is in good agreement with the measured value. What is more, an optical link using an orthogonal-frequency division multiplexing (OFDM) modulation scheme was demonstrated. The transmission data rate increases with the increase of QB thickness from 1.309 to 1.773 Gbps, even though the modulation bandwidth decreases from 245 to 169 MHz. This work provides a way to balance the quantum efficiency and communication performance of green micro-LEDs. [ABSTRACT FROM AUTHOR]

GaN micro-LEDs have been spotlighted as promising candidates for high-speed optical communication, which may become important components in 6G communication blueprint. To achieve a superior network covering sea, land and air for 6G communication, we demonstrated cross-medium communication based on an 80 $\mu$ m double-sided emission micro-LED array. The high enough light output power radiated from both sides of the green micro-LED enabled interference-free signal transmission in different media. Data rates of 1.55 Gbps over the 3 m free-space link and 1.11 Gbps over the 3.4 m underwater link could be achieved simultaneously. Furthermore, parallel-connected micro-LEDs were utilized to demonstrate the feasibility of pattern display and communication, and expected to achieve longer communication distances in media such as underwater channels. [ABSTRACT FROM AUTHOR]

In this paper, a multifunctional ultraviolet-C (UVC) micro-LED with monolithically integrated photodetector (PD) based on AlGaN multiple quantum wells (MQWs) was fabricated. We designed and integrated UVC LED with sizes of 40 and 300  $\mu$ m emitted at 277 nm on a single chip which also serve functions as PDs and further studied the performance of on-chip real-time photodetection. The photocurrent generated from one LED can well reflect the light output power of the adjacent LED. Furthermore, both 40  $\mu$ m UVC micro-LED and 300  $\mu$ m UVC LED play important roles in high speed UVC communication with record bandwidths of 497.58 MHz for 40  $\mu$ m micro-LED and 467.38 MHz for 300  $\mu$ m LED, offering each other as backup light source in high speed UVC communication. And the data transmission rates of 1.6 Gbps for 40  $\mu$ m micro-LED and 1.21 Gbps for 300  $\mu$ m LED over 1 m link based on the 16-ary quadrature amplitude modulation orthogonal frequency division multiplexing (16-QAM-OFDM) with pre-equalization were achieved. The multifunctional UVC micro-LED monolithically integrated PD, without the need for an external PD to monitor the fluctuations in the luminescence, providing high stability for diverse applications, such as spatial wireless communication for 6 G communication. [ABSTRACT FROM AUTHOR]

An integrated device of GaN-based micro-LED and detector was developed for multifunctional applications in visible light communication (VLC). The size of the current spreading layer was used to define the micro-LED size for high-bandwidth transmitter. The device can also be used as high-sensitivity photodetector (PD). In this scenario, the light receiving area is not restricted by the size of the current spreading layer. The size-dependent characteristics of the PD have been investigated in detail. Such integrated devices can be used as both micro-LED and PD for duplex high-speed VLC. Besides, we demonstrated the functions of solid-state lighting and VLC when the device was integrated with broad-area LED, as well as the potential application in micro-LED display combining with VLC. [ABSTRACT FROM AUTHOR]

In this paper, the underwater applications of micro‐LED (light‐emitting diode) in light emission, optical detection, and solar cell are demonstrated. Based on a high‐bandwidth and low‐power micro‐LED array, duplex underwater wireless optical communication (UWOC) and underwater charging are realized. Using the non‐return‐to‐zero on‐off‐keying modulation scheme, the maximum modulation bandwidth and data rate of a micro‐LED transmitter in the 2.3 m duplex UWOC system are 251.3 MHz and 660 Mbps, respectively. In addition, the micro‐LED‐based photodetector can achieve maximum data rates of 52.5 and 60 Mbps at 0 and −5 V in the same UWOC system, respectively. Furthermore, while achieving the communication function, the micro‐LED is used to realize the collection of external light energy, which is successfully employed to drive a 660 nm laser diode, proving the photovoltaic power generation of micro‐LED. This experiment has made a breakthrough in the duplex UWOC system based on an InGaN micro‐LED array, and verifies significant potential of micro‐LED application in the field of duplex UWOC and underwater charging. [ABSTRACT FROM AUTHOR]

In this paper, we present a method for removing a high electron mobility transistor (HEMT) silicon substrate using mechanical grinding and deep silicon etching technology and successfully transferred the epitaxial wafer to a PET substrate to achieve the flexible normally-off HEMT. By testing the output characteristics and transfer characteristics of the Si-substrate HEMT and PET-substrate HEMT, we have demonstrated that the PET-substrate HEMT has excellent performance and successfully achieved the mechanical flexibility. Furthermore, we analyzed the physical mechanisms of the change in PET-substrate and Si-substrate HEMT characteristics, as well as flexible HEMT performance under bent and flattened states. The flexible HEMT array demonstrates significant potential in integration with other flexible devices, such as GaN-based micro-LED arrays. [ABSTRACT FROM AUTHOR]

Abstract: Polycrystalline Ag x (Fe3O4)1−x films (, 0.1, 0.2 and 0.3) have been prepared by the sol–gel method in combination of the spin-coating technique with a precursor solution containing polyvinyl alcohol (PVA) on fused quartz substrates. XRD analysis and SEM images indicate that the Fe3O4 grains are nearly spherical single-domain particles. The coercivities of the films are about 290 Oe for and 360 Oe for , respectively, which are nearly the same as the magnetocrystalline anisotropic effective field of Fe3O4. At 300 K, the film has a maximal magnetoresistance of −8.7% at a magnetic field of 50 kOe and −3.5% at 8.8 kOe, while the pure Fe3O4 film is only −2.2% at 8.8 kOe. This enhancement of the MR can be attributed to the contribution from the spin-dependent scattering at the Ag–Fe3O4 interfaces as well as the spin-polarized tunneling at boundaries of Fe3O4 grains of the spin-polarized electrons. In addition, different MR behaviors for Ag-added Fe3O4 bulk polycrystalline samples and polycrystalline films are discussed. [Copyright &y& Elsevier]

Abstract: A series of bulk polycrystalline (La1−x Sm x )2/3Sr1/3MnO3 () samples were prepared by traditional solid-phase reaction method. Their structures, magnetoresistances and magnetostrictions were studied. The experimental results indicate that with the increase of the Sm content , the average ionic radius of the A site and the Curie temperature of the samples decrease, the maximum of the zero-field resistivity at and corresponding magnetoresistance increase. The magnetostriction measurement shows that the anisotropic magnetostriction coefficient are nearly zero, while the volume magnetostriction coefficients are negative for the and 0.7 samples, which implies that the volumes of the samples are contracted at the temperature just below the Curie temperature, and no saturation occurred even under 7 T strong magnetic field. For the sample, the maximum of is −550×10−6 in the magnetic field of 7 T at 210 K. These experimental results can be interpreted by the viewpoint of phase separation due to the substitution of Sm3+ with smaller ionic radius for La3+ with larger ionic radius in the samples. [Copyright &y& Elsevier]