An investigation of electrical and optical properties of InGaN micro-scale light-emitting diodes (micro-LEDs) emitting at ∼530 nm is carried out, with sizes of 80, 150, and 200 µm. The ITO as a current spreading layer (CSL) provides excellent device performance. Over 10% external quantum efficiency (EQE) and wall-plug efficiency (WPE), and ultra-high brightness (> 10M nits) green micro-LEDs are realized. In addition, it is observed that better current spreading in smaller devices results in higher EQE and brightness. Superior green micro-LEDs can provide an essential guarantee for a variety of applications.

Ultraviolet band C (UV-C) micro light-emitting diodes (micro-LEDs) provide a high energy light emission of 200–280 nm, which are brilliantly utilized in optogenetics, communications, and fluorescence. However, the limited device efficiency notably restricts the grand potential application field. In this work, three types of 20 × 20  μm2 UV-C micro-LEDs with the peak wavelength of 269 nm are fabricated by different etching strategies, including an inductively coupled plasma (ICP), post-ICP tetramethylammonium hydroxide, and a hybrid scheme combining plasma and chemical treatment. By enhancing the radiative recombination and light extraction, the hybrid scheme improves the peak external quantum efficiency of UV-C micro-LEDs to 3.45%, an elevation of 57.5% compared with ICP. A step advance in the forward injection current and ideality factor is also found on the devices fabricated by the hybrid scheme due to better contact on the AlGaN surface.

VR technology has got more and more attention in modern society. However, the core technology of VR, near to eye display technology, is still hard to attain people's expectations [1,2]. Micro‐LED array has great potential in VR display due to the advantage of small size, high brightness, high resolution, low energy consumption, and good monochromaticity compare to the other display technologies. In this paper, we compared Micro‐LED with LCD, OLED, LCoS and DLP, and taking the conclusion that Micro‐LED technology is the best choice for VR display. However, Micro‐LED technology is still facing some challenges. Moreover, a Micro‐LED array‐based VR model was proposed.

We have investigated the thermal characteristics of InGaN-based green micro-light-emitting diodes (micro-LEDs) without the passivation layer in a wide junction temperature range of 298–453 K. The decreased temperature coefficient (dVf/dT) of the device with a smaller device size is attributed to the increased series resistances for the smaller devices, largely affected by the defects due to sidewall damage of the active layer. The ideality factor of 2.02 at 298 K suggests that the charge transport mechanism could be defect-assisted tunneling. In addition, it is observed that the ideality factor decreases with increasing temperature. The results of the C–V measurements suggest similar electron and hole concentrations in the depletion region, leading to a balanced electron–hole recombination in the active layer. It was also found that the temperature-dependent bandgaps of ternary In0.3Ga0.7N obtained from electroluminescence spectra of micro-LEDs agree with the calculated values by using the semi-empirical Varshni relationship.

With the advent of Micro‐LED technology, Micro‐LED light source has been widely used in medical technology due to its unique superior performance. In the field of phototherapy, Micro‐LED has the characteristics of wide spectral range, good monochromaticity, low power consumption and high brightness, which has become the best choice for phototherapy technology. In this paper, we analyze the advantage of Micro‐LED in phototherapy, and optimized phototherapy eye mask, mainly for treating periocular fat granules and acne. Besides, we also introduce the application of Micro‐LED array in the treatment of neonatal jaundice.