Optoelectronic properties of CuO deposited by plasma-enhanced atomic layer deposition

CuO is an important p-type semiconductor with a wide range of potential applications, both on its own, and as a basis for various compounds. However, the ability to deposit CuO thin films and precisely tune their properties using a low temperature process is a limiting factor. In this work, we report a new atomic layer deposition process to deposit CuO thin films using Cu(dmap)₂ and O₂ plasma. We achieve self-limiting deposition behaviour, enabling depositions in the 90–150 °C temperature window. The films are crystalline and display low surface roughness up to 150 °C. More importantly, we also observe significant changes in the optoelectronic properties with deposition temperature, including band gap (1.08–1.16 eV), work function (4.82–5.15 eV), valence band maximum (5.33–5.48 eV) and optical constants. The developed deposition process provides a promising route to fabricate CuO thin films with well-defined and tunable properties at low temperature, which could open doors for future semiconductor applications of copper-based compounds.