Enhanced Light Output Power on Near-Infrared Light-Emitting Diodes with TITO/Ag Multilayer Reflector

A titanium–indium tin oxide (TITO) multilayer reflector was investigated to improve the light efficiency of high-power, near-infrared, light-emitting diodes (NIR-LEDs). The TITO/Ag was fabricated by combining a patterned TITO and an omnidirectional reflector (ODR). For fabricating a high-power NIR-LED, the wafer bond process required the TITO reflective structure, which has patterns filled by AlAu contact metal, bonded directly to the Ag reflector deposited on the silicon wafer. Among Ag-based single- and multilayer reflectors, the TITO/Ag showed the highest reflectance (R = 96%), which was favorable for wafer-bonded high-power NIR-LEDs. Therefore, the TITO/Ag reflector enabled the production of wafer-bonded NIR-LED chips that exhibit superior output performance (190 mW) compared with conventional cases using a single Ag reflector.