EFFECT OF ER DOPANT ON THE PROPERTIES OF IN0.53GA0.47AS LAYERS GROWN BY LIQUID-PHASE EPITAXY

Detailed properties of In(0.53)Ga(0.47)AS layers grown by liquid phase epitaxy from melts containing 0.04 and 0.1 wt % 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 photoluminescen ce measurements indicate that both the donor and the acceptor type imp urities are gettered by Er and the full-width at half-maximum of the m ajor 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 o f 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 acti vation energy of 0.15 eV is revealed from the analysis of the experime ntal data. We associate the 0.17 eV trap with impurities in the materi al. From low temperature photoconductivity and photocapacitance experi ments, we further confirm that Er creates a level located 40 meV above the valence band. Density of this center increases in the material af ter high temperature annealing. We suggest that the Er-related level i s due to Er atoms occupying cation sites in the material and acting as an isoelectronic impurity. (C) 1997 American Institute of Physics.