METHOD FOR PRODUCING AND STRUCTURING A ZINC OXIDE LAYER AND ZINC OXIDE LAYER

• US 20120190209A1
• Filed: 08/07/2010
• Published: 07/26/2012
• Est. Priority Date: 09/02/2009
• Status: Active Grant

• Current Assignee: Forschungszentrum Jã¼Lich GmbH (Bundesrepublik Deutschland)
• Original Assignee: Forschungszentrum Jã¼Lich GmbH (Bundesrepublik Deutschland)
• Inventors: Bunte, Eerke, Owen, Jorj, Huepkes, Juergen
• Granted Patent: US 8,894,867 B2
• Time in Patent Office: Days
• US Class Current: 438/750
• CPC Class Codes: C23C 14/086 of zinc, germanium, cadmium, indium, tin, thallium or bismuth
• CPC Class Codes: C23C 14/5873 Removal of material
• CPC Class Codes: H01L 31/0236 Special surface textures
• CPC Class Codes: H01L 31/02366 of the substrate or of a layer on the substrate, e.g. textured ITO/glass substrate or superstrate, textured polymer layer on glass substrate
• CPC Class Codes: H01L 31/1884 Manufacture of transparent electrodes, e.g. TCO, ITO
• CPC Class Codes: Y02E 10/50 Photovoltaic [PV] energy

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.

Claims

1. A method for producing a zinc oxide layer, in which the crater density and the crater structure of the zinc oxide layer can be adjusted homogeneously and independently of the deposition conditions by etching using hydrofluoric acid comprising at least two etching steps, using hydrofluoric acid in the first etching step and using a different acid, and in particular hydrochloric acid, phosphoric acid, sulfuric acid, nitric acid, acetic acid or citric acid, or another, optionally organic, acid or hydrofluoric acid in a different concentration, in the second etching step, wherein craters having a diameter of less than 300 nm and a crater density of 5 to 100 μ

M<sup>−

2</sup> are established by the first etching step using hydrofluoric acid in a concentration of more than 0.125 wt % to 4 wt %, and the edges of the craters are smoothed by the second etching step.

4. A method according to claim 1, wherein the an etching duration is between 1 and 300 seconds.

19. The method according to claim 1, wherein, if hydrofluoric acid is used in the second etching step, the hydrofluoric acid is used in a concentration of 0.02 wt % to less than 0.125 wt %, whereby craters having diameters of up to 1000 nm are established.

20. A method according to claim 1, wherein a zinc oxide layer having resistivity of less than 10⁻

2 Ohm*cm is etched.

21. A method according to claim 20, wherein a zinc oxide layer is etched which was deposited on a substrate at a static deposition rate of at least 5 nm/s.

2-3. -3. (canceled)

5-18. -18. (canceled)

22. A method for producing a zinc oxide layer, in which the crater density and the crater structure of the zinc oxide layer can be adjusted homogeneously and independently of the deposition conditions by etching using hydrofluoric acid, the etching is carried out using hydrofluoric acid in a concentration of more than 0.125 wt % to 4 wt %, but not 0.25 wt %, so as to establish a crater size having a diameter of less than 300 nm;

and etching is carried out using hydrofluoric acid in a concentration of 0.02 wt % to less than 0.125 wt % so as to establish a crater size having a diameter of more than 300 nm up to 1000 nm.

23. A method according to claim 22, wherein the etching duration is between 1 and 300 seconds.

24. A method according to claim 22, wherein a zinc oxide layer having resistivity of less than 10⁻

2 Ohm*cm is etched.

25. A method according to claim 24, wherein a zinc oxide layer is etched which was deposited on a substrate at a static deposition rate of at least 5 nm/s.