Two dominant deep electron traps, named ME3 and ME6, in Si‐doped AlxGa1−xAs grown by MBE have been studied by Deep Level Transient Spectroscopy (DLTS) and photoluminescence measurements. The change of the two trap concentrations with growth conditions and alloy composition, and the effects of them on photoluminescence intensity are described. The ME3 concentration shows strong alloy composition dependence and has a maximum nearly equal to the doping concentration atxof about 0.4. The ME3 concentration depends linearly on the doping concentration. The ME6 concentration depends strongly on the growth temperature above 720 °C. Group V/III beam flux ratio dependence of ME6 is less than the growth temperature dependence. The growth temperature and beam flux ratio dependences of ME3 are opposite to those of ME6. ME3 has no effect on photoluminescence intensity at room temperature, whereas ME6 reduces the photoluminescence intensity.