Self-assembly of epitaxial monolayers for vacuum wafer bonding

Self-assembled epitaxial metal monolayers can be used for heterointegration of mismatched semiconductors, leading to simultaneously low interfacial resistance and high optical transparency. Lattice-mismatched wafers of Si(100) and Si(111) were bonded at room temperature in situ after vacuum deposition of a single atomic layer of Ag. The interfacial resistance was measured to be 3.9 × 10 − 4 Ω cm 2 and the optical transmission of the interface at 2500 nm is approximately 98%. Electron confinement in ultrathin Ag layers as a possible contributor to the bonding energy.