Wafer bonding of 50-mm diameter GaP to AlGaInP-GaP light-emitting diode wafers

Abstract

The feasibility of wafer bonding 50-nm diameter wafers consisting of GaP-AlGaInP light-emitting diode epitaxial films to GaP substrates is demonstrated. Wafer bonding over the entire wafer area is achieved while maintaining optical transparency and low-resistance electrical conduction at the wafer-bonded interface. Using this technique, visible-spectrum transparent-substrate GaP-AlGaInP/GaP light emitting diodes (LEDs) are fabricated across an entire 50-mm wafer with typical operating voltages <2.1 V at 20 mA and twice the flux of absorbing-substrate GaP-AlGaInP/GaAs LEDs. This large-area wafer-bonding method is further shown to be capable of producing very high efficiency emitters, with an external quantum efficiency of 23.7% (300 K, 20 mA, dc) at 635.6 nm.