Fig. 10.

Donor (ΔE_don) and acceptor (ΔE_acc) dopability windows in the phase stability region calculated from the defect diagrams. The dopability windows at A, B, and C can be directly inferred from the defects diagrams in Fig. 8. The predominant defects that set the dopability windows are labelled in the relevant regions of the phase stability; ΔE_don is set by Te_Sn and Co_i while ΔE_acc is determined solely by Sn_Te. A large dopability window indicates a higher potential for extrinsic doping. Given the large ΔE_don near A, the potential for extrinsic p-type doping is higher under Sn-rich growth conditions. The small or negative ΔE_acc means that extrinsic n-type doping of Co₄Sn₆Te₆ is challenging under any growth conditions.