Thin film Cu2O for solar cell applications

Cu
2
O is a highly relevant material for application as a top cell layer in a tandem solar cell structure. Phase-pure Cu, Cu
2
O and CuO have been deposited with reactive magnetron sputtering by varying the oxygen flow during the deposition from 0 to 2 sccm, using a total flow of 51 sccm. The Cu
2
O films are highly transparent at wavelengths above 520 nm. The highest carrier concentration and mobility of the Cu
2
O films were 2.1 × 10
¹⁵
cm
⁻³
and 18 cm
²
/Vs, respectively, with a resistivity of 163 Ω cm. Two defect levels were discerned from temperature-dependent Hall measurements of 0.16 and 0.23 eV above the valence band maximum.