The spectrum of Zn 3 As 2 -doped sample (Fig. ) demonstrates significantly increased As +3 /As +5 intensity ratio after Ar + etching along with the appearance of As 0 component that becomes exposed after the removal of the oxidized layer via etching, similarly to the Sb 2 O 3 -doped sample, though low intensity As +5 component can still be observed in this case. However, the P-doped sample contains only a P +5 signal (Fig. ) since it is the most stable oxidation state of phosphorus.