The photonic crystal (PC) has been demonstrated to be very effective in improving the extraction efficiency of light-emitting diodes (LEDs). In this paper, high-brightness AlGaInP-based vertical LEDs (VLEDs) with surface PC (SPCLED) and embedded PC (EPCLED) were successfully fabricated. Compared with normal LED (NLED), photoluminescence intensities of SPCLED and EPCLED have been improved up to 30% and 60%, respectively. And the reflection patterns of SPCLED and EPCLED were periodic bright points array, showing the ability to control light in PC. Electroluminescent measurements show that three kinds of LEDs have similar threshold voltages. Simultaneously, the light output power (LOP) of SPCLED and EPCLED has been improved up to 24% and 11% at 200 mA, respectively, in comparison to NLEDs. But the LOP decays earlier for EPCLED due to the excessive heat production. Furthermore, it is demonstrated that the SPCLED and EPCLED luminous uniformity is better. This kind of high brightness PCLED is promising in improving the properties of all kinds of LEDs, especially mini LEDs and micro LEDs.

Overlapping between the quantum-well structure and p–n junction plays an important role in the development of high-efficiency GaAs-based light-emitting diodes (LEDs). In this work, we apply p–n junction engineering to study electro-photoluminescence spectra under open-circuit, forward voltage, and reverse voltage conditions. Through modifying the doping of p-layer or n-layer, luminescent characteristics are apparently improved as a result of the more effective overlapping of the quantum-well structure and p–n junction caused by energy band modification, with the more balanced carrier and stronger confinement in quantum wells. Furthermore, the electroluminescence spectra of all LEDs studied herein are consistent with the photoluminescence results. This work provides an explicit way to tune p- and n-doping to increase emission efficiency, which is important for research and industrial applications.

Plasmonic photodetection based on the hot-electron generation in nanostructures is a promising strategy for sub-band detection due to the high conversion efficiencies; however, it is plagued with the high dark current. In this paper, we have demonstrated the plasmonic photodetection with dark current suppression to create a Si-based broadband photodetector with enhanced performance in the short-wavelength infrared (SWIR) region. By hybridizing a 3 nm Au layer with the spherical Au nanoparticles (NPs) formed by rapid thermal annealing (RTA) on Si substrate, a well-behaved ITO/Au/Au NPs/n-Si Schottky photodetector with suppressed dark current and enhanced absorption in the SWIR region is obtained. This optimized detector shows a broad detection beyond 1200 nm and a high responsivity of 22.82 mA/W at 1310 nm at −1 V, as well as a low dark current density on the order of 10⁻⁵ A/cm². Such a Si-based plasmon-enhanced detector with desirable performance in dark current will be a promising strategy for realization of the high SNR detector while keeping fabrication costs low.

Suppression pre-breakdown in planar separated absorption, grading, charge and multiplication (SAGCM) avalanche photodiodes (APDs) with the help of Floating Guard Ring (FGR) is still a research hotspot. In this paper, a lattice-matched InP/InGaAs-based SAGCM structure is grown by Metal-Organic Chemical Vapor Deposition and thus the planar 50 μm photosensitive area APDs with different FGR structures are fabricated using zinc diffusion process. The effects of the different lengths of FGR (4 μm, 8 μm, 12 μm, 16 μm), and the different distances between FGR and the Zn diffused p+ region (4 μm, 6 μm, 8 μm, 10 μm) on the optoelectrical characteristics are deeply studied. The results from optical microscope, scanning electron microscope and current-voltage curves reveal that there is an optimal length and distance for the punch-through and breakdown voltage. Furthermore, the nA-level dark current, gain ( M ) of up to 10 at breakdown voltage, responsibility as high as 9.01 A/W at M = 10 and quantum efficiency equaling to 72% are also tested and calculated, proving the good performance of our devices. The optimized FGR parameters and related structure are expected to be helpful for obtaining high-performance, small-size InP/InGaAs-based APDs.

To increase the efficiency of silicon heterojunction (SHJ) solar cells (SCs), it is paramount to enhance the utilization of sunlight by light management. In this study, the dependences of weighted reflectance and thus generation current (J _G) for SHJ SCs on different anti-reflective structures are displayed by OPAL2 simulation tool. According to this, SiN _x and SiO₂ films are deposited on front of indium tin oxide (ITO) as multilayer anti-reflection coatings (ARCs). It is demonstrated experimentally that the photovoltaic performance of SHJ SCs can be significantly improved by multilayer ARCs. Especially, with 90/21/40 nm SiO₂/SiN _x /ITO anti-reflective layer structure, the reflectance of SHJ SC is reduced as low as 0.94%, and the current density is shown to be increased by 4.34% compared to the common SCs. This work shows a promising and cost-effective way to achieve higher light utilization and thus promotes photovoltaic characteristics for SHJ SCs.

High-temperature nitridation is commonly thought of as a necessary process to obtain N-polar GaN films on a sapphire substrate. In this work, high-quality N-polar GaN films were grown on a vicinal sapphire substrate with a 100 nm high-temperature (HT) AlN buffer layer (high V/III ratio) and without an intentional nitriding process. The smallest X-ray full width at half maximum (FWHM) values of the (002)/(102) plane were 237/337 arcsec. On the contrary, N-polar GaN film with an intentional nitriding process had a lower crystal quality. In addition, we investigated the effect of different substrate treatments 1 min before the high-temperature AlN layer’s growth on the quality of the N-polar GaN films grown on different vicinal sapphire substrates.