Influence of encapsulation temperature on Ge:Pδ-doped layers

We present a systematic study of the influence of the encapsulation temperature on dopant confinement and electrical properties of Ge:P δ-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 δ 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 cm²/Vs at a carrier density 1.3×10¹⁴ cm^-2, and a 4.2 K phase coherence length of ~180 nm.