A crucible that exploits the observation that molten metal tends to flow toward the hottest regions is disclosed. The crucible includes an interior in which dopant material may be disposed. The crucible has a pathway leading from the interior toward an aperture, wherein the temperature is continuously increasing along the pathway. The aperture may be disposed in or near the interior of the arc chamber of an ion source. The liquid metal flows along the pathway toward the arc chamber, where it is vaporized and then ionized. By controlling the flow rate of the pathway, spillage may be reduced. In another embodiment, an inverted crucible is disclosed. The inverted crucible comprises a closed end in communication with the interior of the ion source, so that the closed end is the hottest region of the crucible. An opening is disposed on a different wall to allow vapor to exit the crucible.