Optical determination of the AlxGa1-xAs energy gap variation versus the Al concentration in MBE-grown samples

The authors have determined the variation of the AlGaAs energy gap (Eg) versus the aluminium concentration x. The x-values are determined by precise X-ray measurements and the values of Eg are deduced from photoluminescence experiments. They find the law, Eg(x)=Eg(O)+1.34x eV, for x<0.45 at T=2 K.