AlGaInP/mirror/Si light-emitting diodes with vertical electrodes by wafer bonding

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 mirror quality after bonding is a confirmed key issue in obtaining vertical MS-LEDs with high brightness. It is found that AuBe thickness has a large effect on the final MS-LED performance due to the difference in the interdiffusion of Be atoms in each mirror structure. The diffusion of excess Be atoms diffusing to the mirror side results in a rougher surface and inferior reflectivity. The luminance intensity of an AlGaInP LED chip (626 nm) with an optimum AuBe thickness can reach a maximum of similar to165 mcd at 20 mA with a forward voltage of 2.1 V. After encapsulation into lamps, the peak power efficiency can reach 21.7%, which corresponds to a 9 mW output at 20 mA. Therefore, the MS structure can be extended to fabricate high-brightness AlGaInP LEDs on Si with conventional vertical electrodes. (C) 2003 American Institute of Physics.