Fabrication and Study on Red Light Micro-LED Displays

A red-light micro LED display made of an AlGaInP epilayer with a resolution of 64 × 32 pixels, a pitch of 175 μm and a luminous area of 1 cm × 0.5 cm was fabricated and characterized in this study. The AlGaInP epilayer was bonded to double polished sapphire substrate by wafer-bonding technique and then removing the absorbing GaAs substrate. In this design, the ITO was applied as one of the conducting electrodes of the emitting surface, which can be beneficial since the emitting light is not shielded by metal electrodes. The other key process for LED panel fabrication is planarization. Polymer material was used to fill the gap between each pixel, which was used to prevent a short or open circuit using the planarization process. The driving mode of this display is passive multi-electrode addressable controlling. The luminance of this micro-LED panel is more than 450 nits with an operating voltage of 3 V which is three times higher than that of the OLED operating in the same driving mode.