Mirror-substrate AlGaInP LEDs for large-area emitter applications

In a previous study, we reported a highly efficient AlGaInP light-emitting diode (LED) with a Au/AuBe/SiO₂/Si mirror substrate (MS) fabricated by wafer bonding, where a planar electrode structure is used. In view of the more efficient epilayer area utilized, AlGaInP/mirror/barrier/Si LEDs with vertical electrodes are proposed in this work. A variety of barrier layers (Pt/Ti, TaN/Ta, and TiN/Ti) have been incorporated into the mirror structure. The quality of the Au/AuBe mirror after bonding is known to be a key issue in obtaining high performance MS-LEDs. The large-area AlGaInP emitters (1.2 × 1.2 mm²) show that its luminous intensity and output power can reach 6 candelas and 81 mW under an injection current of 1 A and 300 mA, respectively. The dominant wavelength shifts ∼5 nm under an injection current from 20 mA to 1 A. Based on these results, it can be concluded that the wafer-bonded AlGaInP epilayers with mirror substrates have high potential in high-brightness, high-power and large-area LED applications.