NOVELTY - The method comprises depositing a first zinc oxide layer onto a substrate (41), reducing a zinc precursor content in a deposition environment, treating the first zinc oxide layer with a mixture of diborane and water to form coating seeds on a surface of the first zinc oxide layer, depositing a second zinc oxide layer onto the first zinc oxide layer, and subsequently depositing third zinc oxide layer onto the substrate. The step of reducing the zinc precursor content in the deposition environment comprises stopping an inflow of the zinc precursor material into the deposition environment.    USE - The method is useful for coating a substrate in a deposition environment for manufacturing a solar cell such as thin film solar cells and microcrystalline solar cells.    ADVANTAGE - The method is capable of effectively, rapidly and economically coating the substrate in a deposition environment with reduced energy consumption thus improving the quality, light scattering and light trapping property of the solar cell and reducing the reflection losses and defects of the solar cell.    DETAILED DESCRIPTION - The method comprises depositing a first zinc oxide layer onto a substrate (41), reducing a zinc precursor content in a deposition environment, treating the first zinc oxide layer with a mixture of diborane and water to form coating seeds on a surface of the first zinc oxide layer, depositing a second zinc oxide layer onto the first zinc oxide layer, and subsequently depositing third zinc oxide layer onto the substrate. The step of reducing the zinc precursor content in the deposition environment comprises stopping an inflow of the zinc precursor material into the deposition environment, pumping the deposition environment to provide a lower precursor concentration, and purging the deposition environment by introducing water, diborane, nitrogen and/or hydrogen. The step of depositing the first zinc oxide layer and/or the step of depositing the second zinc oxide layer are performed by a low-pressure chemical vapor deposition process using different deposition chambers. The first zinc oxide layer is treated with a mixture of diborane and water in a relation lying in a range of 1:2 to 1:4. The mixture of diborane and water is partly removed from the substrate before reducing the zinc precursor content in the deposition environment. The step of treating the first zinc oxide layer with the mixture of diborane and water is performed in a further treatment chamber whilst the substrate is delivered from the first deposition chamber to the second deposition chamber. The first zinc oxide layer is deposited to have an equal degree of doping compared to the second zinc oxide layer and to have a greater thickness compared to the second zinc oxide layer. The three layers have a degree of doping subsequently decreasing from the first zinc oxide layer to the following zinc oxide layers. A middle zinc oxide layer has a degree of doping smaller compared to the adjacent layers. The step of reducing the zinc precursor content in the deposition environment and the step of treating the first zinc oxide layer with the mixture of diborane and water are performed during respective deposition steps. A composition and/or a temperature is modified during the step of depositing the first zinc oxide layer and/or the step of depositing the second zinc oxide layer. An INDEPENDENT CLAIM is included for a solar cell.    DESCRIPTION OF DRAWING(S) - The diagram shows schematic view of a solar cell.    Solar cell (40)    Substrate (41)    Electrode layer (42)    P-i-n junction (43)    P-type-layer (44)    N-type-layer. (46)