Weak localization and weak antilocalization in doped Ge Sn layers with up to 8% Sn.

Low-temperature magnetoresistance measurements of n- and p-doped germanium-tin (Ge Sn ) layers with Sn concentrations up to 8% show contributions arising from effects of weak localization for n-type and weak antilocalization for p-type doped samples independent of the Sn concentration. Calculations of the magnetoresistance using the Hikami-Larkin-Nagaoka model for two-dimensional transport allow us to extract the phase-coherence length for all samples as well as the spin-orbit length for the p-type doped samples. For pure Ge, we find phase-coherence lengths as long as (349.