Photodetector having improved photoresponsitivity over a broad wavelength region
AssigneeFujitsu Quantum Devices Limited
InventorsYoshihiro Yoneda, Ikuo Hanawa
Life of this patent
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Abstract
A photodetector includes an optical absorption layer having a thickness d optimized with regard to a voltage applied across the optical absorption layer such that there occurs an increase of optical absorption coefficient at the wavelength of 1580 nm or longer.
Claims10
A photodetector having an optical absorption layer, said optical absorption layer having a bandgap Eg(eV), an absorption edge wavelength λe (μm) and an optical absorption coefficient provided by
- 4 α ( ϵ ( λ ) ) = α ( ξ ) = 0.18510 - 2 · 4.3410 6 0.0124 · k · [ ξ ( [LeftBracketingBar] A i ( - ξ ) [RightBracketingBar] ) 2 + ( [LeftBracketingBar] ⅆ ⅆ ξ A i ( - ξ ) [RightBracketingBar] ) ] 2 , ( A )
- wherein
- 5 A i ( - ξ ) = 1 π ∫ 0 ∞ cos [ 1 3 t 3 + ( - ξ ) t ] ⅆ t ,
- Ai(−ξ)being an Airy function,
- 6 ϵ ( λ ) = E ( λ ) - Eg k , E g = 1.2398472447 n ( λ e ) · λ e , E ( λ ) = 1.2398472447 n ( λ ) · λ , n ( λ ) = 1 + [ 6432.8 + 2949810 146 - 1 λ 2 + 25540 41 - 1 λ 2 ] · 10 - 8 , ( B ) k = 0.0124 [ V d ] 2 3 , ( C )
- ∈(λ), n(λ), E(λ) being respectively a dielectric constant, a refractive index and a bandgap at the wavelength of an incident light, k being a coefficient obtained from a voltage V(V) applied to said optical absorption layer and a layer thickness d(m) of said optical absorption layer,
- wherein said thickness d(m) of said optical absorption layer is set with respect to said voltage V(V) applied to said optical absorption layer so as to satisfy a relationship
- 106≦V/d≦107. (D)
A method of operating a photodetector having an optical absorption layer, said optical absorption layer having a bandgap Eg(eV), an absorption edge wavelength λe (μm), and an optical absorption coefficient provided by
- 7 α ( ϵ ( λ ) ) = α ( ξ ) = 0.18510 - 2 · 4.3410 6 0.0124 · k · [ ξ ( [LeftBracketingBar] A i ( - ξ ) [RightBracketingBar] ) 2 + ( [LeftBracketingBar] ⅆ ⅆ ξ A i ( - ξ ) [RightBracketingBar] ) ] 2 , ( A )
- wherein
- 8 A i ( - ξ ) = 1 π ∫ 0 ∞ cos [ 1 3 t 3 + ( - ξ ) t ] ⅆ t ,
- Ai(−ξ)being an Airy function,
- 9 ϵ ( λ ) = E ( λ ) - Eg k , E g = 1.2398472447 n ( λ e ) · λ e , E ( λ ) = 1.2398472447 n ( λ ) · λ , n ( λ ) = 1 + [ 6432.8 + 2949810 146 - 1 λ 2 + 25540 41 - 1 λ 2 ] · 10 - 8 , ( B ) k = 0.0124 [ V d ] 2 3 , ( C )
- ∈(λ), n(λ), E(λ) being respectively a dielectric constant, a refractive index and a bandgap at the wavelength of an incident light, k being a coefficient obtained from a voltage V(V) applied to said optical absorption layer and a layer thickness d(m) of said optical absorption layer,
- said method comprising the step of applying an electric field E(V/m) such that there is satisfied a relationship
- 106≦V/d≦107. (D)
Dependencies are inferred from the claim text.