Alternative Substrates for Materials Integration

The recent demonstration of twist bonded GaAs substrates offers the potential to develop universally compliant substrates upon which almost any III-V or related semiconductor can be grown without lattice mismatch induced defect formation. Compliant substrates would rapidly expand and improve a number of device applications, such as Sb-based detectors and a wide range of InGaAlAsP devices, which are currently limited by lattice mismatching constraints. Initial demonstrations of twist bonded GaAs have been limited in area. In order to fully evaluate the potential of this technology within the context of standard device fabrication and testing protocol, full wafers (22' dia.) must be produced and evaluated. Wafer flatness and cleanliness are the key limitations to achieving atomic scale bonding over large areas. In order to achieve uniform bonding, it is necessary to develop an etch stop epitaxial structure that results in a clean, smooth epi surface and also enables efficient removal of the sacrificial GaAs substrate. In Phase I, Epitronics proposes to develop an optimum etch stop epitaxial structure that will enable the fabrication of large area twist bonded substrates. In Phase II, we will demonstrate large area twist bonded substrates suitable for epitaxial growth and device fabrication and testing.