VANDERWAALS BONDING OF GAAS ON PD LEADS TO A PERMANENT, SOLID-PHASE-TOPOTAXIAL, METALLURGICAL BOND

Various forms of wafer bonding have now emerged as a serious competitor to heteroepitaxy for optoelectronic integration of dissimilar semiconductor materials. Among the types of wafer bonding, perhaps the most flexible is that which employs free-standing III-V films as created by epitaxial liftoff. For some purposes, weak Van der Waals forces provide an adequate bond between the native oxides of the III-V film and its new substrate. If the substrate is coated by palladium however, a low temperature solid-phase-topotaxial reaction occurs, producing oriented Pd4GaAs under the GaAs film. In effect, the topotaxy comes about through mechanical contact alone. The resulting metallurgical bond is an ohmic contact, a thermal contact and a robust, permanent, adherent contact.