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.
Bibliographical noteFunding Information:
V.J.S. is supported by AFOSR (grant no. FA9550-17-1-0377) and ARO (grant no. W911NF-16-2-0194). M.A.S.R.S., B.U. and S.D.S. acknowledge support from the US Department of Energy, Office of Science, Basic Energy Sciences under award no. DE-SC0018041. S.R.B. acknowledges support from NSF grant nos. DMR-1839175 and CCF-1838435. We acknowledge computational support from the Minnesota Supercomputing Institute (MSI).