Strain-engineered high-responsivity MoTe2 photodetector for silicon photonic integrated circuits
R Maiti and C Patil and MASR Saadi and T Xie and JG Azadani and B Uluutku and R Amin and AF Briggs and M Miscuglio and D Van Thourhout and SD Solares and T Low and R Agarwal and SR Bank and VJ Sorger, NATURE PHOTONICS, 14, 578-+ (2020).
In integrated photonics, specific wavelengths such as 1,550 nm are preferred due to low-loss transmission and the availability of optical gain in this spectral region. For chip-based photodetectors, two- dimensional materials bear scientifically and technologically relevant properties such as electrostatic tunability and strong light-matter interactions. However, no efficient photodetector in the telecommunication C-band has been realized with two-dimensional transition metal dichalcogenide materials due to their large optical bandgaps. Here we demonstrate a MoTe2-based photodetector featuring a strong photoresponse (responsivity 0.5 A W-1) operating at 1,550 nm in silicon photonics enabled by strain engineering the two-dimensional material. Non-planarized waveguide structures show a bandgap modulation of 0.2 eV, resulting in a large photoresponse in an otherwise photoinactive medium when unstrained. Unlike graphene-based photodetectors that rely on a gapless band structure, this photodetector shows an approximately 100-fold reduction in dark current, enabling an efficient noise-equivalent power of 90 pW Hz(-0.5). Such a strain- engineered integrated photodetector provides new opportunities for integrated optoelectronic systems.
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