Effect of rare earth addition on liquid phase epitaxial InP-based semiconductor layers

The influence of rare earth (RE) element (Ho, Er or Nd) addition during liq uid phase epitaxial growth (LPE) on the electro-optical properties of InP a nd GaInAsP semiconductor layers has been studied. The effect of Nd admixtur e is reported for the first time. Series of InP-based layer samples were pr epared by LPE from the melt containing 0-0.35 wt.% of RE admixture. Tempera ture-dependent Hall effect and capacitance-voltage curves show a quite dram atic impact of Er or Nd on donor and free-carrier concentrations: they were decreased by as much as three orders of magnitude in some cases. Low-tempe rature photoluminescence (PL) spectra have been measured for various levels of excitation power. The major manifestation of the RE admixture was the p ronounced narrowing of PL curves and the corresponding appearance of the fi ne features in the excitonic band, characteristic of pure material, low in defects. The effects are attributed to RE atoms acting as very efficient ge ttering agents. (C) 1999 Elsevier Science S.A. All rights reserved.