Effect of rare earth addition on GaAs-based layers grown by liquid phase epitaxy

Photoluminescence and electrical measurements were carried out for studying the influence of rare-earth elements (Yb) concentration in the Ga melt on the electronic and structural properties of LPE GaAs epilayers. It was shown that at low concentration the main role of Yb is the gettering of residual impurities in the melt. At the same time, Yb addition in the melt changes the heterogeneous equilibrium by changing the stoichiometry of epilayers (increase of $V_{\text{Ga}}$). But at further increase of Yb concentration in the melt Yb begins to enter in the Ga-sublattice and cluster with deviation from the stoichiometry. An optimum concentration of Yb exists at which high-purity and stoichiometric epilayers for a device application can be obtained