Enhancement of the light trapping by double-layered surface texture of ITO/AZO and AZO/AZO transparent conductive films

• Published in: Materials letters 2014-05, Vol.123, p.14-18
• Main Authors: Jiang, Q.J., Lu, J.G., Yuan, Y.L., Cai, H., Zhang, J., Deng, N., Ye, Z.Z.
• Format: Article
• Language: English
• Subjects: Semiconductors; Sputtering; Surfaces; Texture; Thin films
• ISSN: 0167-577X; 1873-4979
• DOI: 10.1016/j.matlet.2014.02.074

Double-layered surface textures of ITO/AZO (In2O3:Sn/ZnO:Al) and AZO/AZO transparent conductive films are conducted with a process of deposition, first-etching, re-deposition and re-etching. Light trapping ability can be greatly reinforced by the induced double broad feature distributions. For the re-etching process, stronger etching pits with 400–600nm feature sizes and ~68nm Root Mean Square (RMS) roughness are obtained in AZO/AZO films compared to that of the first-etching samples. The use of Fe(III) catalyst can greatly increase the etching rate. Diffuse transmittance with the largest value (56.97%) is observed for the double-layered AZO–HCl/AZO–HCl+FeCl3 sample due to the formation of crater-like morphology in the mezzanine and the surface of the films. The double-textured AZO samples exhibit higher haze values (50.73% and 55.50%) at 550nm, corresponding to the AZO/AZO samples using HCl+FeCl3 or HCl alternately. For ITO related samples, the resistivity keeps the order of 10−4Ωcm after the re-deposition. While, for AZO/AZO films, a slight increment of resistivity and carrier concentration is observed due to the chemical etching. These double-textured structures imply that the films have potential application in thin film silicon (TFS) solar cells for light trapping. •Double-layered surface textures are designed to improve the light trapping.•400–600nm feature sizes and ~68nm RMS value are obtained in AZO/AZO films.•The Fe(III) catalyst can greatly increase the etching rate.•The double-textured AZO samples exhibit higher haze values (>50%) at 550nm.