Characteristics of High-Power Impulse Magnetron Sputtering ITO/Ag/ITO Films for Application in Transparent Micro-LED Displays

In this study, a blue transparent micro-LED display with a chip size of 20 μm × 20 μm, a pixel density of 152 PPI, a pixel spacing of 150 μm, and a resolution of 64 × 32 has been fabricated. ITO/Ag/ITO transparent layers were deposited by high-power impulse magnetron sputtering. Sheet resistance was used to analyze the electrical properties of the indium tin oxide (ITO) layers, whereas scanning electron microscopy, transmission electron microscopy, and atomic force microscopy were used to examine the surface morphology. These results demonstrate that the ITO/Ag/ITO structure with 20 nm thick Ag has a lower sheet resistance (3.36 Ω/sq) and sufficient visible light transmittance (80.45%). The visible light transmittance of the ITO/Ag/ITO layers increased to 86% after rapid thermal annealing. In addition, surface roughness was minimized, and sheet resistance was further reduced, resulting in ohmic contact on n-GaN that is suited for applications involving transparent micro-LED displays.