The overall objective of this research is to develop source materials for doping AIGaAs. We compared Er(C5H5)3 to Er{N[Si(CH3)3]2)3 for purity, decomposition kinetics and doping of germanium films deposited from Ge(CH3)4 in a hydrogen atmosphere. Cyclopentadienyl erbium left large amounts of carbon both in pure metal films, and in the germanium film, at low pressure and temperatures to 850°C. Bis-(tri-methylsilyl) erbium amide decomposed cleanly without carbon, nitrogen or silicon in the deposited film.