Selective chemical-vapor deposition of variously sized germanium dots, from 25 to 100 nm in diameter and 2 to 12 nm high, was induced by applying a +9.5 V sample bias to a variable-temperature ultrahigh-vacuum scanning tunneling microscope. In the presence of 0.5-2 mTorr of germane gas (2% germane in helium). Deposition occurs only in the presence of germane provided that the silicon (111) substrate is adequately cleaned and hydrogen passivated. In addition, the deposits formed at 370 K were found to have greater size uniformity than those formed at room temperature. Attempts to deposit lines of germanium resulted in the formation of a series of clusters. Two possible explanations are given for this tendency toward clustering : current tracking and a Stranski-Krastanov growth mode. Finally, scanning tunneling I-V spectra of the deposits are characteristic of a semiconductor material.