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.