Infrared Reflection Spectra ofGa1−xInxAs: A New Type of Mixed-Crystal Behavior

The infrared reflection spectra of ${\mathrm{Ga}}_{1-x}{\mathrm{In}}_x\mathrm{As}$ crystals reveal a new type of mixed-crystal behavior in which two bands are seen, one near the InAs Reststrahlen region and one which shifts monotonically with $x$ between the InAs and GaAs Reststrahlen regions. A discussion is given in terms of postulated criteria using local and gap modes.