The doping of germanium with zinc from a remote, temperature-stabilized sou
rce was studied under microgravity. A nominally undoped Ge-crystal was grow
n by the Gradient-Freeze technique with the melt surface being in permanent
contact with a gaseous atmosphere of zinc. The dopant and carrier concentr
ations in the solidified Germanium were measured by SIMS, Hall and resistan
ce measurements and compared with the results of a terrestrial reference ex
periment as well as with concentration profiles calculated on the basis of
the thermodynamics of the: growth system. The results prove the possibility
of vapour phase doping under microgravity. Moreover, the Zn-concentration
at the initial phase boundary even agrees well with the equilibrium value,
strongly indicating a nearly homogeneous distribution of the dopant within
the melt before the crystallization.