WAFER BONDING FOR MOCVD ALGaAS LEDS WITH TRANSPARENT SUBSTRATE GaP

Abstract

GaAs substrate absorbs light produced by epitaxial grown AlGaAs layer, since GaAs has smaller band gap than AlGaAs. To achieve Light Emitting Diode (LED) with back-emitting characteristics, the objective of this project is to bond GaP, which has a larger bandgap than AlGaAs, onto AlGaAs surface. Surface treatment procedure and bonding recipe were developed and strong bonding, which can withstand lapping force and etching chemicals, was achieved. Bonding quality was tested using various characterization tools and methods, including optical microscope, scanning acoustic microscopy (SAM), scanning electronic microscopy (SEM) and Instron tensile strength testing machine. Plasma assisted wafer bonding and optimum plasma condition are also explored.