Low-temperature buffer layer-assisted heteroepitaxial growth of γ-CuI thin films by pulsed laser deposition: Tailoring electrical properties

As the first discovered p-type transparent conductive material, copper(I) iodide (CuI) is considered the most competitive p-type candidate in the field of transparent electronics. Herein, we introduced a low-temperature buffer-layer-assisted strategy to grow γ-CuI with significantly improved structural quality and electrical transport properties by pulsed laser deposition. By adjusting the growth temperature, we can manipulate the rotation domain structure, control the hole concentration Nh from 1014 to 1019 cm−3, and achieve mobility μh = 25 cm2 V−1 s−1 being similar to that of bulk CuI. Based on the temperature-dependent Hall-effect measurement, the ionization energy of a shallow acceptor of EI,S = 137 ± 8 meV and that of a deeper acceptor of EI,D = 262 ± 23 meV were determined. This grown strategy not only enables high-quality CuI film preparation, but also to tailor their electrical properties for integration with n-type semiconductors in transparent electronic circuits.