Embodiments of the invention provide an apparatus and a process for generating a chemical precursor used in a vapor deposition processing system. The apparatus includes a canister (e.g., ampoule) having a sidewall, a top, and a bottom encompassing an interior volume therein, inlet and outlet ports in fluid communication with the interior volume, and a thermally conductive coating disposed on or over the outside surface of the canister. The thermally conductive coating is more thermally conductive than the outside surface of the canister. The thermally conductive coating may contain aluminum, aluminum nitride, copper, brass, silver, titanium, silicon nitride, or alloys thereof. In some embodiments, an adhesion layer (e.g., titanium or tantalum) may be disposed between the outside surface of the canister and the thermally conductive coating. In other embodiments, the canister may contain a plurality of baffles or solid heat-transfer particles to help evenly heat a solid precursor therein.