Pseudodielectric functions of InGaAs alloy films grown on InP

We present room-temperature pseudodielectric function spectra <epsilon> of InxGa1-xAs films grown on (100) InP by solid-source molecular-beam epitaxy. A wet-chemical etching procedure is used to remove overlayers and obtain the best approximation to the bulk dielectric responses epsilon of the films. By line shape fitting, we determined the x dependences of the E-1 and E-1+Delta(1) critical-point energies and that of the Delta(1) bowing parameter. The results are in good agreement with the predictions of a universal tight-binding model. (C) 2002 American Institute of Physics.