GaAs layers were heavily doped with liquid source diethyltellurium (DETe) during organometallic vapor phase epitaxy. Samples were characterized by Hall effect measurements and transmission electron microscopy (TEM). The electron concentration was observed to saturate at 3 X 10(19) cm(-3) for high DETe flows, which is independent of growth temperature in the investigated range from 475 to 600 degrees C. TEM examination revealed the presence of precipitates in layers doped above the saturation level. The precipitates were Te-rich by energy dispersive x-ray analysis. Electron diffraction study showed that they have the zinc-blende structure with a lattice constant of 6.5 Angstrom. The appearance of tellurides at high doping levels indicates that the formation of a second phase could be one of the main mechanisms responsible for the carrier saturation in Te-doped GaAs. The liquid source DETe causes persistent memory effects associated with the adsorption of DETe on the stainless steel tube walls of the gas distribution system.