The window for the ALE self limited growth of GaAs can be expanded by reducing the gas phase decomposition. We found that the exposure time to TMGa flux is critical and has to be reduced for ALE to be achieved at high growth temperature. An ALE reactor was used which allows minimum gas heating, short exposure time, and sudden termination of the gas exposure without relying on the diffusion of gases away from the substrate surface. ALE was achieved in the 450–700 °C temperature range. Carbon doping in the 1015–1020/cm3range was also achieved by adjusting the exposure time and the growth temperature. The combined role of gas phase decomposition and surface reaction are proposed to explain these results.