Interface structure of InGaAs wafers bonded using thin amorphous Ge films in vacuum

Abstract

This study examines room-temperature bonding of InGaAs wafers in vacuum using thin amorphous Ge (a-Ge) films. InGaAs wafers bonded using 0.5–1-nm-thick a-Ge film on respective sides show great bonding strength comparable to the fracture strength of InGaAs after annealing at 340 °C. High-resolution images obtained using transmission electron microscopy show no vacancy at the bonded a-Ge/a-Ge interface and no clear damage of the deposited a-Ge films on the crystal lattices of the InGaAs surfaces. Analysis using electron energy-loss spectroscopy reveals a slight inter-diffusion of Ge and In at the a-Ge/InGaAs interface.