Reactive magnetron sputtering of Cu2O: Dependence on oxygen pressure and interface formation with indium tin oxide

Thin films of copper oxides were prepared by reactive magnetron sputtering and structural, morphological, chemical, and electronic properties were analyzed using x-ray diffraction, atomic force microscopy, in situ photoelectron spectroscopy, and electrical resistance measurements. The deposition conditions for preparation of Cu(I)-oxide (Cu2O) are identified. In addition, the interface formation between Cu2O and Sn-doped In2O3 (ITO) was studied by stepwise deposition of Cu2O onto ITO and vice versa. A type II (staggered) band alignment with a valence band offset ΔEVB = 2.1–2.6 eV depending on interface preparation is observed. The band alignment explains the nonrectifying behavior of p-Cu2O/n-ITO junctions, which have been investigated for thin film solar cells.