Ga1−xAlxAs purification during its liquid phase epitaxial growth in the presence of Yb

Abstract
The influence of Yb added to the melt, on the near‐band‐gap emission of Ga1−xAlxAs grown by liquid phase epitaxy, is reported. No characteristic Yb3+ emission is found, but a pronounced narrowing of the bound‐exciton spectrum is observed for Yb concentrations in the Ga melt below 100 ppm. A similar effect is seen in conduction band to acceptor transitions, for which the smallest linewidth observed is limited by fluctuations in composition and agrees well with the currently accepted 66:34 band‐offset partition between the conduction and valence bands of GaAs/Ga1−xAlxAs heterojunctions in the direct band‐gap range.