Embodiments of the invention provide apparatuses and methods for depositing materials on substrates during vapor deposition processes, such as atomic layer deposition (ALD). In one embodiment, a chamber contains a substrate support with a receiving surface and a chamber lid containing an expanding channel formed within a thermally insulating material. The chamber further includes at least one conduit coupled to a gas inlet within the expanding channel and positioned to provide a gas flow through the expanding channel in a circular direction, such as a vortex, a helix, a spiral or derivatives thereof. The expanding channel may be formed directly within the chamber lid or formed within a funnel liner attached thereon. The chamber may contain a retaining ring, an upper process liner, a lower process liner or a slip valve liner. Liners usually have a polished surface finish and contain a thermally insulating material such as fused quartz or ceramic. In an alternative embodiment, a deposition system contains a catalytic water vapor generator connected to an ALD chamber.