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.