Abstract: A deposition system includes a process tube aligned vertically with a substrate holder therein positioned horizontally and perpendicular to a vertical tube axis. Through a bottom or top flange a first gas line connector is for injecting a first gas and a reactant gas connector is for injecting at a reactant gas. A feed line is coupled between the reactant gas connector and a reactant gas distributor having apertures for flowing the reactant gas towards a substrate. A vapor generating showerhead includes a gas distribution plate having flow distributing apertures on a precursor boat having gas inlets fluidically coupled to precursor holder trenches that hold a vapor generating material. The gas inlets have a flow path for flowing the first gas over the vapor generating material for generating a reactant vapor that flows out of the flow distributing aperture toward the substrate.