We compare optical characteristics of black phosphorus photodetectors integrated with a stripe waveguide and a ridge waveguide by optical field intensity and absorption spectrum, which proves that the stripe waveguide is better for enhancing the optical absorption of black phosphorus photodetector. The strain effect on the band structure of black phosphorus is investigated using the first-principles method based on density functional theory (DFT). The band structure of 5-layer BP experiences a direct-indirect-direct transition and a semiconductor-metal transition (SMT) when applied different strains. As a result, the cut-off wavelength and the responsivity of this strained BP photodetector can reach 3.76μm and 0.48 A/W respectively. In a word, the waveguide-integrated black phosphorus photodetector under strain for mid-infrared range may promote potential novel optoelectronic device applications based on two-dimensional materials in the future.
In this work, a fully strained GeSn photodetector with Sn atom percent of 8% is fabricated on Ge buffer on Si(001)
substrate. The wavelength λ of light signals with obvious optical response for Ge0.92Sn0.08 photodetector is extended to 2
μm. The impacts of compressive strain introduced during the epitaxial growth of GeSn on Ge/Si are studied by
simulation. Besides, the tensile strain engineering of GeSn photonic devices is also investigated. Lattice-matched
GeSn/SiGeSn double heterostructure light emitting diodes (LEDs) with Si3N4 tensile liner stressor are designed to
promote the further mid-infrared applications of GeSn photonic devices. With the releasing of the residual stress in Si3N4
liner, a large biaxial tensile strain is induced in GeSn active layer. Under biaxial tensile strain, the spontaneous emission
rate rsp and internal quantum efficiency ηIQE for GeSn/SiGeSn LED are significantly improved.
In this paper, tensile strained Ge0.90Sn0.10 photodiode with different architectures integrated with Si3N4 liner stressor for mid-infrared applications are theoretically investigated. Ge0.90Sn0.10 fin and waveguide photodiodes wrapped in the Si3N4 liner stressor are designed and the strain distribution is studied by the finite element simulation. A large tensile strain is induced in Ge0.90Sn0.10 with the Si3N4 liner stressor expanding. The energy band structure of tensile strained Ge0.90Sn0.10 is calculated using k⋅p theory. The direct bandgap Eg,Γ of Ge0.90Sn0.10 under tensile strain is significantly reduced, which results in a large red shift of the cut-off wavelength of strained Ge0.90Sn0.10 devices. As the Si3N4 liner stressor expands by 1.5%, 25.1% and 48.7% reduction of Eg,Γ are achieved in tensile strained Ge0.90Sn0.10 fin and waveguide photodiodes, respectively, compared to the unstrained device. The cut-off wavelengths of tensile strained Ge0.90Sn0.10 fin and waveguide devices are extended to 3.68 μm and 5.37 μm, respectively. Introducing tensile strain into GeSn by tensile strain liner stressor provides an effective method for extending the detection spectrum of GeSn photodiodes to mid-infrared wavelength, e.g. 5μm.
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