Reliability aspects of hydrogen-doped indium oxide

We demonstrate an alternative route to reliably prepare hydrogen-doped indium oxide (In2O3:H). The common hydrogen source, water vapor, was substituted in our process by hydrogen and oxygen gas. The resulting films showed similar optical and electrical properties. Nevertheless, the process using gaseous hydrogen led to a simplification of the deposition process. By replacing the hydrogen source we increased the reproducibility of the electrical film properties significantly, thus, paving the way for a reliable device implementation of the material. Furthermore, we investigated the degradation behavior of In2O3:H under damp heat conditions as preliminary test for long-term durability in photovoltaic devices. The results revealed a degradation of the electrical properties that differs in detail regarding the amorphous and polycrystalline material. In the amorphous material, the main degradation is caused by loss of charge carriers, whereas in the polycrystalline material a drop of the charge carrier mobility causes a significant rise of the resistivity. However, we show that the relative degradation of the In2O3:H films is similar to other transparent contacts that are implemented in solar cells. Finally, we demonstrate that the degradation of the charge carrier mobility in the polycrystalline In2O3:H films is completely reversible by vacuum annealing at 200 °C