High performance IWO thin films deposited with a new hybrid technology for solar cell applications

Transparent conductive oxides (TCOs) are essential for solar cell technologies, providing high optical transmission and electrical conductivity. This paper proposes a new Hybrid Plasma Deposition (HPD) technique for TCOs, that combines a very low-pressure microwave plasma and DC thermal evaporation. This technique has not yet been reported and the first results are presented here as a proof of concept. Plasma diagnostic indicates ion energies below 30 eV, significantly lower than those of conventional sputtering, offering a promising route to a new deposition technique compatible with sensitive substrates. The deposited IWO (Tungsten-doped Indium Oxide) films exhibit uniformly crystallized grains, optical transmission greater than 80 % in the visible spectrum, low resistivity of 3.21 × 10⁻⁴ Ωcm and mobility of 41 cm² × V^{-1 × s-1} with a corresponding carrier concentration of 4.76 × 10²⁰ cm⁻³. After annealing at 200 °C, the resistivity slightly increased to 3.8 × 10⁻⁴ Ωcm, while mobility improved significantly to 86 cm² × V^-1 × s^-1, with a carrier concentration of 1.90 × 10²⁰ cm⁻³ making these films highly suitable for photovoltaic applications. These films were integrated into silicon heterojunction (SHJ) solar cells as transparent electrodes. The solar cells exhibited a high efficiency of 23.89 %, demonstrating the potential of HPD in enhancing solar cell performance.