Comparing metal oxide thin films as transparent p-type conductive electrodes

The development of transparent and p-type conductive layers remains a challenge to achieve more efficient hole collection and to combine with the most common n-type counterparts into transparent p-n junctions. Here, several candidates based on abundant materials: Cu2O, NiO and SnO have been prepared, characterized and comparatively evaluated. Thin-film deposition methods (evaporation and sputtering) have been used along with thermal treatments (oxidation and sulfurization) to maximize the transmittance and conductivity for each material. The highest quality is achieved by Cu-x (S, O) layers prepared by sulfurization of Cu2O at 250 degrees C. Besides, the NiO films obtained by reactive sputtering at room temperature have a good quality to be applied on heat-sensitive substrates.