Electron beam deposition (EBD) is a maskless technique suitable for the fabrication of nanometer scale structures. Metals can be deposited from an organometallic gas, but simultaneous carbon deposition typically yields grossly impure (∼25% metal) deposits. We have found that the metal content of the deposited solid is dramatically improved by performing the whole EBD process in a reactive gaseous environment containing a source of oxygen (O2or H2O) in addition to the organometallic gas. With simple procedures we prepared Au deposits showing significantly diminished C content (up to 50% metal) as the partial pressure ofO2(orH2O) is increased in the gas. ©1995 American Institute of Physics.