Influence of encapsulation temperature on Ge:P δ -doped layers

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 {approx}530 deg. C provides the best compromise between high crystal quality and minimal dopant redistribution, with an electron mobility {approx}128 cm{sup 2}/Vs at a carrier density 1.3x10{sup 14} cm{sup -2}, and a 4.2 K phase coherence length of {approx}180 nm.

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