Study of a low power plasma reactor for the synthesis of doped and undoped zinc oxide used as the window layer in CIGS solar cells

The Low Power Plasma Reactor is an original process which allows a rapid deposition of ZnO thin films with calibrated thickness. The deposition is performed by the spraying of an aqueous precursor solution in cold plasma. The final optimizations allow high average growth rates reaching 0.6 nm/s. Characterization of films (XRD, FTIR, Transmittance, resistivity measures) reports the expected crystallinity, composition, the needed transparency and a calculated optical gap value ranging between 3.2-3.3 e V. The resistivity of layers was studied to be decreased in order to improve the electric properties of thin films. The performances of Cu(In,Ga)Se2 solar cells with a plasma sprayed intrinsic ZnO (i-ZnO) layer showed efficiencies around 15% (equivalent value with classic sputtered i-ZnO).