Reflection high‐energy electron diffraction intensity dynamic behavior was examined on GaAs, AlAs, and Al0.5Ga0.5As layers using As4and/or As2flux to establish optimum growth conditions for heterointerfaces. Results show that As4is preferable for the growth of AlAs and Al0.5Ga0.5As, while As2is better for GaAs. This finding is explained on the basis of the expected dynamic surface kinetic processes. Low‐temperature photoluminescence line width of a quantum well (20 monolayer GaAs well/100 monolayer Al0.5Ga0.5As barriers) grown under the optimized growth condition is 4.5 meV.