Pulsed Electron Beam Deposition of Zinc Oxide Thin Films

Thin films made from transparent conducting oxides are used as contact electrodes for solar cells due to their high electrical conductivity and transparency in the visible spectral range. Sustaining these opposite properties is challenging but pulsed plasma technologies are ideally placed in this field due to the processes that can be carefully tailored to a specific application. Here, we report on pulsed electron beam deposition as a low-cost and sustenable plasma technology for oxide thin films with tunable physical properties with application in photovoltaics [1-3]. It has similar features with the pulsed laser deposition: the pulsed nature of process, the anisotropy of the ablation plasma and the high energy of species arriving at the substrate. The main difference between these film growth technologies consists of the use of electrons in place of photons leading to an extension of the range of materials that could be ablated due the specific electron-matter interaction. We present epitaxial undoped and doped zinc oxide thin films obtained at relatively low substrate temperatures with tailorable film physical properties due to the precise control of the growth parameters. Indeed, modifications of the of the substrate temperature, gas or pressure lead to strong effects on the optical transparency and/or electrical conductivity. These effects will be discussed in relation to the film composition, demonstrating the role of dopants and/or oxygen in film properties. [1] M. Nistor et al., RSC Adv. <b>6</b>, 41465 (2016); [2] M. Nistor, et al., J. Phys. D: Appl. Phys. <b>41</b>, 165205 (2008); [3] M. Nistor et al., Appl. Surf. Sci. <b>563</b>, 150287 (2021).