Systems and methods for supplying a precursor material for an atomic layer deposition (ALD) process are provided. A gas supply provides one or more precursor materials to a deposition chamber. The deposition chamber receives the one or more precursor materials via an input line. A gas circulation system is coupled to an output line of the deposition chamber. The gas circulation system includes a gas composition detection system configured to produce an output signal indicating a composition of a gas exiting the deposition chamber through the output line. The gas circulation system also includes a circulation line configured to transport the gas exiting the deposition chamber to the input line. A controller is coupled to the gas supply. The controller controls the providing of the one or more precursor materials by the gas supply based on the output signal of the gas composition detection system.