Cu2(Sn1-xMgx)Se3 (Mg-x-CTSe) bulks at x = 0, 0.05, 0.1, 0.15, and 0.2 were prepared at 550 °C for 2 h. Defect chemistry was studied by measuring structural and electrical properties of Mg-doped Cu2SnSe3 as a function of ...