Spectral Shift of Photoluminescence of Highly Doped GaAs Epitaxial Layers Grown by MOCVD

The photoluminescence spectra of Se-doped and Si-doped GaAs epitaxial layers grown by metalorganic chemical vapor deposition (MOCVD) were measured and compared. The spectral shift of Se-doped samples changes only with the carrier concentration, which can be explained by the Moss-Burstein shift, while that of Si-doped samples depends not only on the carrier concentration but also on growth rates and V/III mole fractions. It became apparent from X-ray diffraction that the lattice constant began to decrease in highly Si-doped layers and that the anomalous spectral shifts are caused by the lattice compression originating from a high density of [SiGa-SiAs] pairs incorporated in highly Si-doped layers.