InGaAs Detector Parameters
InₓGa₁₋ₓAs band gap, cutoff wavelength, QE, responsivity, generation dark current, NEP and D* for SWIR p-i-n photodiodes.
Band Gap E_g
0.7373 eV
Vurgaftman 2001, x = 0.53, 300 K
Cutoff λ_c
1682 nm
QE @ 1300 / 1550 nm
94.6 / 81.8 %
R @ 1550 nm
1.023 A/W
Intrinsic Density n_i
6.30e+11 cm⁻³
Dark Current
3.028e-10 A
generation limit 3.028e-10 A
NEP @ 1550 nm
9.629e-15 W/√Hz
D* @ 1550 nm
3.284e+12 cm·Hz^½/W
E_g(x, T) = (1−x)·E_g,GaAs(T) + x·E_g,InAs(T) − 0.477·x(1−x) eV, E_g(T) = E_g(0) − αT²/(T+β)
α = 2.4×10⁴ cm⁻¹·√(E − E_g/eV), QE = (1 − R)·(1 − e^(−α·d))
I_gen = q·n_i·d·A/τ_g, I_dark = I_gen·(1 − e^(qV/2k_BT)), i_n = √(2q·I_gen)
Model and references
Textbook approximation. A standard approximation from the literature (for example paraxial, plane-wave or Gaussian-beam), valid within the range the page states. About the tiers
Band gap from Vurgaftman's Varshni sets with bowing 0.477 eV (0.7373 eV, cutoff 1682 nm at x = 0.53, 300 K). Absorption α = A·√(E − E_g), A fitted to Adachi's model within ±12 % from 0.95 to 1.62 µm. The absorber is a fully depleted slab; dark current is space-charge generation q·n_i·d·A/τ_g with n_i scaled from 6.3e11 cm⁻³ through the gap only. Diffusion current from the neutral layers, which dominates many devices above room temperature, surface leakage and tunnelling are left out. The QE chart starts at 950 nm, the lower edge of the α fit, for a bare absorber with no InP window. The noise √(2q·I_gen) is the shot noise in reverse bias and the Johnson noise at zero bias.
- Vurgaftman I., Meyer J. R., Ram-Mohan L. R. (2001). Band parameters for III–V compound semiconductors and their alloys. J. Appl. Phys. 89, 5815–5875. Varshni sets (Tables I–X) and the Ga₁₋ₓInₓAs bowing C = 0.477 eV (Table XIII). doi:10.1063/1.1368156
- Paul S., Roy J. B., Basu P. K. (1991). Empirical expressions for the alloy composition and temperature dependence of the band gap and intrinsic carrier density in GaₓIn₁₋ₓAs. J. Appl. Phys. 69, 827–829. n_i = 6.3e11 cm⁻³ for Ga₀.₄₇In₀.₅₃As at 300 K (as tabulated in the Ioffe NSM archive). doi:10.1063/1.348919
- Adachi S. (1989). Optical dispersion relations for GaP, GaAs, GaSb, InP, InAs, InSb, AlₓGa₁₋ₓAs, and In₁₋ₓGaₓAsᵧP₁₋ᵧ. J. Appl. Phys. 66, 6030–6040. In₀.₅₂Ga₀.₄₈As n, k as tabulated at refractiveindex.info; basis of the absorption fit. doi:10.1063/1.343580
- Sze S. M., Ng K. K. (2007). Physics of Semiconductor Devices, 3rd ed. Wiley, ch. 2. Space-charge generation current q·n_i·W/τ_g and its e^(qV/2k_BT) bias dependence. doi:10.1002/0470068329