Low Dark Current and High Responsivity 1020nm InGaAs/GaAs Nano-Ridge Waveguide Photodetector Monolithically Integrated on a 300-mm Si Wafer

Abstract

We report on high-quality InGaAs/GaAs multi-quantum well waveguide photodetectors, monolithically integrated through metalorganic vapor-phase selective-area epitaxial growth and contact metallization in a 300-mm CMOS pilot line. The photodetectors are implemented using the nano-ridge engineering concept, leveraging aspect-ratio trapping in combination with precise control of the nano-ridge cross section dimensions and composition. The InGaAs/GaAs p-i-n nano-ridge photodetectors are shown to achieve high internal responsivities of up to 0.65 A/W at -1 V bias and 1020 nm wavelength. A clear correlation is observed between measured responsivity and contact-plug design, correlating well with simulation models. In addition, a record-low dark current density of 1.98 × 10 <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">-8</sup> A/cm <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sup> and low absolute dark currents of <; 1 pA are demonstrated, illustrating the high quality of the III-V materials and effective in-situ InGaP surface passivation layers. Initial RF measurements suggest RC-limited photodetection bandwidths in the GHz range. These results illustrate the strong potential of the III-V/Si nano-ridge epitaxy and waveguide device concept, to complement the Silicon Photonics toolbox with high-quality, high-throughput III-V functionality.