A Flip-Chip AlGaInP LED with GaN/Sapphire Transparent Substrate Fabricated by Direct Wafer Bonding

A red-light AlGaInP light emitting diode (LED) is fabricated by using direct wafer bonding technology. Taking N-GaN wafer as the transparent substrate, the red-light LED is flip-chiped onto a structured silicon submount. Electronic luminance (EL) test reveals that the luminance flux is 130% higher than that of the conventional LED made from the same LED wafer. Current--voltage (I--V) measurement indicates that the bonding processes do not impact the electrical property of AlGaInP LED in the small voltage region (V<1.5V). In the large voltage region (V>1.5V), the I--V characteristic exhibits space-charge-limited currents characteristic due to the p-GaAs/n-GaN bonding interface.