Five electron traps were detected successfully in heavily Si-doped GaAs and AlxGa1-xAs of low Al content with a Si concentration of above 1×1019 cm-3 using deep level transient spectroscopy. The junctions were grown by liquid phase epitaxy and were strongly compensated. The traps were investigated for functions of the Si concentration and the AlAs mole fraction. The traps are discussed in terms using their spectra and concentration as opposed to the previous results which used point defects in the GaAs and AlGaAs. The traps show distinctive features, which can be attributed to strongly Si-compensated crystals. Three traps among them were confirmed to be DX centers.