Photo-capacitance measurements at photon energies ranging from 0.64 to 1.27eV were performed on layers which had been grown by liquid phase epitaxy and which were doped with various amounts of In and Sb. Two hole traps, with optical ionization energies of 0.65 and 0.79eV, were detected and were assumed to arise from 2 levels which were associated with the reported B hole trap. In addition, the A hole trap which was usually found in liquid phase epitaxial GaAs was also detected here by using optical deep-level transient spectroscopy. The results of trap density measurements, as functions of the iso-electronic dopant concentration, indicated that VGa was an active constituent of the hole traps in liquid phase epitaxial GaAs. The concentration of the 0.79eV trap was reduced in material with a high Sb concentration. An analysis of the photo-capacitance data, using existing theoretical models, revealed the existence of an electron trap (with an activation energy of 0.75eV) in heavily Sb-doped material. This trap was identified with the second charge state of the SbGa electron trap which had previously been observed in bulk and metalorganic vapor phase epitaxial Sb-doped GaAs. The sharp reduction in the 0.79eV hole trap density in Sb-doped material was explained by assuming that the GaAsVGa- complex was its source.

K.Mallik, S.Dhar: Physica Status Solidi B, 1994, 184[2], 393-402