GaAs/Si direct wafer bonding.
(a) Configuration schematic of the I–V measurement for the direct-bonded GaAs/Si heterointerfacial electrical characteristics. A positive bias voltage was applied from the GaAs side. (b, c) I–V characteristics of the direct-bonded GaAs/Si heterointerfaces with varying doping concentrations and bonding temperature. (d, e) Calculated profiles of the conduction and valence band edges across the (d) p-GaAs/p-Si and (e) p-GaAs/n-Si heterointerfaces with varying doping concentrations. The inset in e shows a closeup around the origin. (f) Cross-sectional transmission electron microscope image of a direct-bonded p+-GaAs/p+-Si heterointerface. (g–i) Selected-area diffraction patterns at the same heterointerface as of f for regions around 70 nm in radius centred (g) 80 nm above the interface, (h) at the interface and (i) 80 nm below the interface, identified as single-crystal GaAs, a mixture of single-crystal GaAs and Si and single-crystal Si, respectively.