A system, comprising: a vaporizer vessel having one or more interior walls enclosing an interior volume ; and a plurality of reagent support trays , wherein: each of the plurality of the reagent support trays includes a support surface having a top face configured to support a supply of the source reagent material and a bottom face; and the plurality of reagent support trays is configured to be vertically stackable within the interior volume to form a stack of reagent support trays , wherein one or more of the plurality of reagent support trays is configured to redirect a flow of a gas passing between two or more adjacent reagent support trays in the stack of reagent support trays so as to cause the flow of gas to interact with the source reagent material in a particular reagent support tray of the plurality of reagent support trays before passing into a next of the plurality of reagent support trays in the stack of reagent support trays, the reagent support trays being divided into sections by a plurality of dividers extending fully across the support surface and centrally intersecting one another on the support surface, the dividers having channels therethrough for gas to flow through the channels from below the bottom face to above the top face. a vaporizer vessel having one or more interior walls enclosing an interior volume ; and a plurality of reagent support trays , wherein: each of the plurality of the reagent support trays includes a support surface having a top face configured to support a supply of the source reagent material and a bottom face; and the plurality of reagent support trays is configured to be vertically stackable within the interior volume to form a stack of reagent support trays , wherein one or more of the plurality of reagent support trays is configured to redirect a flow of a gas passing between two or more adjacent reagent support trays in the stack of reagent support trays so as to cause the flow of gas to interact with the source reagent material in a particular reagent support tray of the plurality of reagent support trays before passing into a next of the plurality of reagent support trays in the stack of reagent support trays, the reagent support trays being divided into sections by a plurality of dividers extending fully across the support surface and centrally intersecting one another on the support surface, the dividers having channels therethrough for gas to flow through the channels from below the bottom face to above the top face. each of the plurality of the reagent support trays includes a support surface having a top face configured to support a supply of the source reagent material and a bottom face; and the plurality of reagent support trays is configured to be vertically stackable within the interior volume to form a stack of reagent support trays , wherein one or more of the plurality of reagent support trays is configured to redirect a flow of a gas passing between two or more adjacent reagent support trays in the stack of reagent support trays so as to cause the flow of gas to interact with the source reagent material in a particular reagent support tray of the plurality of reagent support trays before passing into a next of the plurality of reagent support trays in the stack of reagent support trays, the reagent support trays being divided into sections by a plurality of dividers extending fully across the support surface and centrally intersecting one another on the support surface, the dividers having channels therethrough for gas to flow through the channels from below the bottom face to above the top face. <EOS>