Detailed properties of In0.53Ga0.47As layers grown by liquid phase epitaxy from melts containing 0.04 and 0.1 wt &percent; Er are reported. The carrier concentration in the material is reduced by almost two orders of magnitude as a result of Er doping. Low temperature photoluminescence measurements indicate that both the donor and the acceptor type impurities are gettered by Er and the full-width at half-maximum of the major peak is reduced to 4 meV for the layer with the highest Er doping. From deep level transient spectroscopy experiments on undoped layers, we confirm the presence of an electron trap with activation energy of 0.17 eV. Density of this trap is reduced by more than two orders of magnitude in the Er doped material and another electron trap with activation energy of 0.15 eV is revealed from the analysis of the experimental data. We associate the 0.17 eV trap with impurities in the material. From low temperature photoconductivity and photocapacitance experiments, we further confirm that Er creates a level located 40 meV above the valence band. Density of this center increases in the material after high temperature annealing. We suggest that the Er-related level is due to Er atoms occupying cation sites in the material and acting as an isoelectronic impurity. ©1997 American Institute of Physics.