Iterative composition optimization in Fe₂VA1–based thin-film thermoelectrics using single-target sputtering

Abstract

Magnetron sputtering inherently exhibits the advantage of dislodging particles from the target in a ratio equivalent to the target stoichiometry. Nevertheless, film compositions often deviate due to element-dependent scattering with the working gas, necessitating the adjustment of the sputtering process. In this work, we explore an unconventional approach to addressing this issue, involving the employment of an off-stoichiometric target. The required composition is obtained through an iterative process, which is demonstrated by Fe2VAl and Fe2V0.9Ti0.1Al films as case studies. Ultimately, the correct stoichiometry is obtained from Fe1.86V1.15Al0.99 and Fe1.88V1.02Ti0.13Al0.97 targets, respectively. Despite the thermoelectric properties falling below expectations, mainly due to imperfect film crystallization, the strategy successfully achieved the desired stoichiometry, enabling accurate film synthesis without the need for advanced sputtering setups.