High-Speed InGaAs Photodetectors by Selective-Area MOCVD Toward Optoelectronic Integrated Circuits

We report selective-area growth of high-crystalline-quality InGaAs-based photodetectors with optimized InP/GaAs buffers on patterned (100)-oriented silicon-on-insulator (SOI) substrates by metal-organic chemical vapor deposition. The composite GaAs and InP buffer was grown using a two-temperature method. The island morphology of the low-temperature GaAs nucleation layer inside the growth well of the SOI substrate was optimized. A medium temperature GaAs layer was inserted prior to the typical high-temperature GaAs to further decrease the dislocation densities and antiphase boundaries. Both normal-incidence photodetectors and butt-coupled waveguide photodetectors were fabricated on the same substrate and showed a low dark current and high-speed performance. This result demonstrates a good potential of integrating photonic and electronic devices on the same Si substrate by direct epitaxial growth.