Direct wafer bonding of III-V compound semiconductors for free-material and free-orientation integration

This paper describes the use of direct wafer bonding technique to implement the novel concept of "free-material and free-orientation integration" which we propose. The technique is applied for various wafer combinations of an InGaAsP material system, and the properties of the bonded structures are studied in terms of the crystalline and electrical characterization through transmission electron microscope, X-ray diffraction, and so on. This technique's advantage for use in the fabrication of lattice-mismatched structures is confirmed by the crystalline characterization, together with its second advantage of enabling bonded structures with an orientation mismatch, is investigated. The high crystalline quality of the bonded structures with both lattice and orientation mismatches is proved, and the electrical property of the bonded interface is examined for some of them. We show a practicability in a laser fabricated on a lattice- and orientation-mismatched structure by direct bonding. The results demonstrate the remarkable feasibility of using the direct wafer bonding technique to obtain integrated structures of material- and orientation-mismatched wafers with satisfactory quality.