Electroreflectance in Amorphous Germanium Revisited

Two years ago Piller, Seraphin, Markel, and Fischer reported electroreflectance measurements on disordered germanium; their results allowed the interpretation that the $E_0$, $E_0+{\Delta }_0$ doublet is still present in the completely amorphous state. I demonstrate here that the electroreflectance peak positions are determined entirely by interference effects in the thin-film sample, and hence have no bearing on the electronic structure of amorphous Ge.