GE-AU EUTECTIC BONDING OF GE (100) SINGLE-CRYSTALS

We present preliminary results on the eutectic bonding between two {10 0} Ge single crystal surfaces using thin films of Au ranging from 900 angstrom/surface to 300angstrom/surface and Pd (10% the thickness of A u). Following bonding, plan view optical microscopy (OM) of the cleave d interface of samples with Au thicknesses less-than-or-equal-to 500 a ngstrom/surface show a eutectic morphology more conducive to phonon tr ansmission through the bond interface. High resolution transmission el ectron microscopy (HRTEM) cross sectional interface studies of a 300 a ngstrom/surface Au sample show [100] epitaxial growth of Ge. In sectio ns of the bond, lattice continuity of the Ge is apparent through the i nterface. TEM studies also reveal [110] heteroepitaxial growth of Au w ith a Au-Ge lattice mismatch of less than 2%. Eutectic bonds with 200 angstrom/surface Au have been attained with characterization pending. An optical polishing technique for Ge has been optimized to insure int imate contact between the Ge surfaces prior to bonding. Interferometry analysis of the optically polished Ge surface shows that surface heig ht fluctuations lie within +/-150 angstrom across an interval of 1 mm. Characterization of phonon transmission through the interface is disc ussed with respect to low temperature detection of ballistic phonons.