Fig. 2

STEM/EDX elemental maps representing Bi distribution in samples S1 (a) and S2 (b). Details of Bi, Ga and As elemental maps corresponding to the cluster marked with a white rectangle in Fig. 1b reveal a drop in As and Ga signals where there is a high Bi region. c Bi content profiles along [001] direction extracted after integration of an area of around 130 nm from the EDX map of samples S1 (blue line) and S2 (black line). Similar features were observed in the intensity profiles at low magnification shown in Fig. 1c