Method for producing and structuring a zinc oxide layer and zinc oxide layer
AssigneeForschungszentrum Juelich GmbH
InventorsEerke Bunte, Jorj Owen, Juergen Huepkes
Life of this patent
Estimating the term…
Abstract
Disclosed is a method for producing ZnO contact layers for solar cells. The layers are etched using hydrofluoric acid so as to generate a texture.
Claims18
A method for producing a zinc oxide layer on a flexible or rigid substrate by depositing the zinc oxide layer onto said substrate, in which the zinc oxide layer has a crater density and a crater structure that can be adjusted homogeneously and independently of deposition conditions by etching, the method comprising the steps of sputtering zinc oxide on to a substrate to provide a deposited zinc oxide layer, etching the deposited zinc oxide layer in at least first and second etching steps, etching in the first etching step with hydrofluoric acid in a concentration of more than 0.125 wt % to 4 wt %, etching in the second etching step with one of an acid that is not hydrofluoric acid or hydrofluoric acid in a concentration different from the hydrofluoric acid concentration employed in the first etching step, whereby in the first etching step craters are formed in the deposited zinc oxide layer that have a diameter of less than 300 nm, the craters having a density of 5 to 100 μm−2, and the craters have edges that are smoothed by the etching in the second etching step.
A method for producing a zinc oxide layer on a flexible or rigid substrate by depositing the zinc oxide layer onto said substrate, in which the zinc oxide layer has a crater density and the crater structure of the zinc oxide layer can be adjusted homogeneously and independently of the deposition conditions, the method comprising the steps of sputtering zinc oxide on to a substrate to provide a deposited zinc oxide layer, etching the deposited zinc oxide layer in first and second etching steps, etching with hydrofluoric acid in the first etching step in a concentration of more than 0.125 wt % to 4 wt %, whereby a crater size having a diameter of less than 300 nm is provided;
- and etching in the second etching step with hydrofluoric acid in a concentration of 0.02 wt % to less than 0.125 wt %, whereby a crater size having a diameter of more than 300 nm up to 1000 nm is provided.
A method for producing a zinc oxide layer on a substrate, in which the produced zinc oxide layer has a double structure surface of first craters within second craters to achieve a roughness for scattering light, wherein crater density and crater size is homogeneously and reproducibly controlled according to applied etching solutions and etching processes, the method comprising:
- sputtering zinc oxide on the substrate by sputtering to achieve a deposited zinc oxide layer having a c-axis texture;
- and
- etching the deposited layer in first and second etching processes to achieve said homogeneously and reproducibly controlled crater density and crater size of said first craters within second craters;
- and
- wherein said etching comprises etching the deposited layer in the first etching process using a first etching solution to produce said first craters, and etching the deposited layer in the second etching process using a second etching solution to achieve said second craters, said second craters being on average larger than craters formed by the first etching process, said first craters occurring at a crater density of 5 to 100 μm−2 which is greater than a crater density of said second craters;
- and
- wherein the first etching solution comprises using hydrofluoric acid at a concentration of more than 0.125 wt % to 4 wt %, and the second etching solution comprises one of an acid that is not hydrofluoric acid or hydrofluoric acid in a concentration different than the hydrofluoric acid concentration employed in the first etching process.
Dependencies are inferred from the claim text.