Fabrication of Cu-Zn-Sn-S-O Thin Films by the Electrochemical Deposition Method and Application to Heterojunction Cells

摘要

A new multinary semiconductor Cu_2ZnSnS_(4-x)O_x (CZTSO), which does not contain toxic elements and expensive rare metals, was fabricated by the electrochemical deposition (ECD) method. CZTSO thin films were deposited onto indium tin oxide (ITO-) coated glass substrates by DC and two-step pulsed ECD from aqueous solutions containing CuSO_4, ZnSO_4, SnSO_4, and Na_2S_2O_3. The films deposited by pulsed ECD contained smaller amount of oxygen than those deposited by DC ECD. The films had band gap energies in a range from 1.5 eV and 2.1 eV. By a photoelectrochemical measurement, it was confirmed that CZTSO films showed p-type conduction and photosensitivity. CZTSO/ZnO heterojunctions exhibited rectification properties in a current-voltage measurement.