Quantum efficiency as a function of wavelength

[gnurf]

I'm trying to reproduce the plot in the attached figure. I know the band-gap energies, so I was hoping there was some simple way I could get the quantum efficiency as a function of wavelength. I read on wiki that Energy(eV) = 1240/wavelength(nm), so I mechanically plugged those in, and got

GaInP (Eg=1.85eV): 670 nm
GaAs (Eg=1.42eV): 873 nm
Ge (Eg=0.67eV): 1851 nm

Other than that the respective wavelengths came out in the right order, it didn't really help all that much. Is there some magical quantum mechanical formula I could drink in order to make that plot?

EDIT: I should probably have posted this in the QM sub-forum. My apologies.

 

[rastiya]

E=h$\upsilon$
E=$\frac{hc}{\lambda}$
E=$\frac{h\ =\ 4.135\ \times\ 10^{-15}\ eV\ s\\times\ 3\ \times\ 10^{17}\nm}{\lambda}$
E=$\frac{1240}{\lambda}$