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 liquid phase epitaxial growth (LPE) on the electro-optical properties of InP and GaInAsP semiconductor layers has been studied. The effect of Nd admixture is reported for the first time. Series of InP-based layer samples were prepared by LPE from the melt containing 0–0.35 wt.% of RE admixture. Temperature-dependent Hall effect and capacitance–voltage curves show a quite dramatic 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-temperature photoluminescence (PL) spectra have been measured for various levels of excitation power. The major manifestation of the RE admixture was the pronounced narrowing of PL curves and the corresponding appearance of the fine features in the excitonic band, characteristic of pure material, low in defects. The effects are attributed to RE atoms acting as very efficient gettering agents.