Micro-light-emitting diodes (μLEDs) are semiconductor devices that have been shown to have higher luminous efficacy, higher contrast ratio, and higher energy efficiency than existing mainstream technologies based on liquid crystals or organic LEDs (OLEDs). Portable display applications such as wearable devices and head-up display are some of the interesting applications of μLED displays. However, this technology has not yet been mass-produced for commercial devices due to process yields, costs, and manufacturability issues. This article presents a novel technology for the heterogeneous integration of a μLED matrix display with bipolar complementary metal-oxide- semiconductor (CMOS) DMOS (BCD) circuits that could improve manufacturability by eliminating the need for a dedicated bond stack in the bump-bonding process. To validate the concept, custom high-performance, 2-D arrays of parallel-addressed GaN blue μLEDs matrices were fabricated. The individual μLED pixel diameters are 20 and 50 μm, respectively, and the overall dimension of the array is 650 μm2. In addition, a μLED display driver-integrated circuit (IC) with a compact size of 3×4.4 mm ² has been designed, implemented, and verified experimentally for the μLED matrices. Measured output optical power-forward bias current-forward bias voltage (P-I-V) curves of the individual μLED pixel are shown. The 4 × 4 μLED matrix has also been successfully driven using active-matrix driving and display pictures to demonstrate the function of active-matrix driving are presented.

Light-emitting diodes (LEDs) are solid-state devices that are highly energy efficient, fast switching, have a small form factor, and can emit a specific wavelength of light. The ability to precisely control the wavelength of light emitted with the fabrication process enables LEDs to not only provide illumination, but also find applications in biology and life science research. To enable the new generation of LED devices, methods to improve the energy efficiency for possible battery operation and integration level for miniaturized lighting devices should be explored. This paper presents the first case of the heterogeneous integration of gallium nitride (GaN) power devices, both GaN LED and GaN transistor, with bipolar CMOS DMOS (BCD) circuits that can achieve this. To validate this concept, an LED driver was designed, implemented and verified experimentally. It features an output electrical power of 1.36 W and compact size of 2.4 × 4.4 mm². The designed fully integrated LED lighting device emits visible light at a wavelength of approximately 454 nm and can therefore be adopted for biology research and life science applications.

LEDs are highly energy efficient and have substantially longer lifetimes compared to other existing lighting technologies. In order to facilitate the new generation of LED devices, approaches to improve power efficiency with increased integration level for lighting device should be analysed. This paper proposes a fully on-chip integrated LED driver design implemented using heterogeneous integration of gallium nitride (GaN) devices atop BCD circuits. The performance of the proposed design is then compared with the conventional fully on-board integration of power devices with the LED driver integrated circuit (IC). The experimental results confirm that the fully on-chip integrated LED driver achieves a consistently higher power efficiency value compared with the fully on-board design within the input voltage range of 4.5–5.5 V. The maximal percentage improvement in the efficiency of the on-chip solution compared with the on-board solution is 18%.