  We present a systematic study of the influence of the encapsulation
temperature on dopant confinement and electrical properties of Ge:P delta-doped
layers. For increasing growth temperature we observe an enhancement of the
electrical properties accompanied by an increased segregation of the
phosphorous donors, resulting in a slight broadening of the delta-layer. We
demonstrate that a step-flow growth achieved at 530 C provides the best
compromise between high crystal quality and minimal dopant redistribution, with
an electron mobility ~ 128 cm^2/Vs at a carrier density 1.3x10^14 cm-2, and a
4.2 K phase coherence length of ~ 180 nm.
