Epitaxial Zinc Stannate (Zn₂SnO₄) Thin Film for Solar Cells

Epitaxial Zn2SnO4 thin films were fabricated using rf magnetron sputtering and characterized via X-ray diffraction (XRD) to investigate its structural behaviors. XRD measurements indicate high-quality single crystal films of (400) orientation. The growth follows cubic-to-cubic alignment with the epitaxial relationship of Zn2SnO4[001]//MgO[001] in the out-of-plane direction and Zn2SnO4[110]//MgO[110] in the in-plane direction. The Hall mobility of 88.5 ± 6.2 cm2 V–1 s–1 was achieved. The Zn2SnO4 films had average optical transmittance ≥90% and a band gap of 3.582 ± 0.082 eV. In the optical pump–THz probe spectroscopy result, a relatively longer charge-carrier lifetime, τl = 2158.89 ps, was achieved.