Speaker
Description
Nonlinear Photonic Integrated Circuits (NPICs) are promising platforms for next generation compact precision measurement and telecommunication technologies, for example, the generation of compact optical frequency combs. As the nonlinear optical generation efficiency depends on the intensity of light travelling in NPIC’s waveguiding structures, waveguide materials with high linear and nonlinear refractive indices are desired. In this context, Gallium Phosphide (GaP) is a promising waveguide material, as it has high linear (>3) and nonlinear (>10-17m2/W) refractive indices at telecommunications wavelengths. Additionally, its crystal lattice parameters are matched to Silicon (Si), enabling direct heteroepitaxial growth. When followed by direct bonding on SiO2 coated Si substrate, highly confining GaP on insulator waveguides can be formed.
Here we report on the progress towards demonstrating the GaP on insulator waveguide platform, in particular the wafer bonding and backside removal of thin-film GaP grown on Si wafers to SiO2 coated Si host substrates. The GaP thin-film was grown using Molecular Beam Epitaxy (MBE). For the bonding process, a thin layer of SiO2 or TiO2 was deposited using Atomic Layer Deposition (ALD). These surfaces were activated using O2 plasma and treated with water to improve adhesion when the two facets are contacted during prebonding. Afterwards, the samples were annealed on a hotplate at 200°C overnight. The Si substrate on which the GaP was grown was then removed using a KOH solution with the stack upside down. after which the resulting GaP thin-film surface was analyzed.
In conclusion, we report a fabrication process enabling direct bonding and backside removal of GaP grown on Si to SiO2 coated Si substrates, paving the way to an easy-to-process nonlinear photonic waveguide platform with strong nonlinearity. In the future, we will fabricate highly confining nonlinear optical GaP waveguides.
| I am the presenting author | Yes |
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