Wafer bonding of 75 mm diameter GaP to AlGaInP-GaP light-emitting diode wafers

The AlGaInP/GaP wafer-bonded transparent-substrate (TS) light-emitting diodes (LEDs) have been shown to exhibit luminous efficiencies exceeding many conventional lightning sources including 60 W incandescent sources. This paper will demonstrate the feasibility of scaling wafer bonding technology to 75 mm diameter wafers and some of the unique challenges associated with this scaling. The quality and uniformity of bonding were characterized via scanning acoustic microscopy, white light transmission measurements, full-wafer mapping of parametric performance, and operating life tests. High bonding yields over large areas facilitate low-cost, high-volume fabrication of TS AlGaInP/GaP LEDs, and thus, further enable these devices to compete with other lighting sources.