Systems and methods for atomic layer deposition

An atomic layer deposition (ALD) method can include pulsing a first reactant vapor into a reactor assembly. The first reactant vapor is supplied to a first reactant gas line. An inactive gas is supplied to a first inactive gas line at a first flow rate. The first reactant vapor and the inactive gas are fed to the reactor assembly by way of a first feed line. The reactor assembly is purged by supplying the inactive gas to the first inactive gas line at a second flow rate higher than the first flow rate. A first portion of the inactive gas can be fed back along a diffusion barrier portion of the first reactant gas line to provide an inert gas valve (IGV) upstream of the first inactive gas line. A second portion of the inactive gas can be fed to the reactor assembly by way of the first feed line.