848 ppi high-brightness active-matrix micro-LED micro-display using GaN-on-Si epi-wafers towards mass production

In this paper, fabrication processes of a 0.55-inch 400 × 240 high-brightness active-matrix micro-light-emitting diode (LED) display using GaN-on-Si epi-wafers are described. The micro-LED array, featuring a pixel size of 20 µm × 20 µm and a pixel density of 848 pixels per inch (ppi), was fabricated and integrated with a custom-designed CMOS driver through Au-Sn flip-chip bonding. Si growth substrate was removed using a crack-free wet etching method. Four-bit grayscale images and videos are clearly rendered. Optical crosstalk is discussed and can be mitigated through micro-LED array design and process modification. This high-performance, high-resolution micro-LED display demonstration provides a promising and cost-effective solution towards mass production of micro-displays for VR/AR applications.