Some properties of Cu2SnSe3, Cu2GeSe3 and other A2IBIVC3VI compounds
Attempts were made to synthesize nine A2IBIVC3VIcompounds (AI = Cu,Ag; BIV = Ge,Sn,Pb; CVI = Se,Te) by solidification from stoichiometric melts. Ternary phases were obtained for four of the five combinations involving Cu. Ingots of Cu2SnSe3 and Cu2GeSe3 were essentially single-phase, indicating that these compounds are congruently melting. The Cu2GeTe3 ingot contained a small percentage of GeTe, while the ternary phase made up only about half the Cu2SnTe3. No ternary phase was detected for Cu2PbSe3 or for any of the four combinations involving Ag. The electrical resistivity and Hall coefficient have been measured down to 77 K in Cu2SnSe3 and Cu2GeSe3, and the temperature dependence indicates the presence of two band conduction. Both undoped compounds were p-type with room temperature carrier concentrations greater than 1×1018/cm3. Doping Cu2SnSe3 with I, Sb, In or Zn resulted in hole concentrations greater than 1020/cm3. The optical absorption edge occurs at 0.5 eV for Cu2SnSe3 and at 0.85 eV for Cu2GeSe3.