Electrochemical texturing of Al-doped ZnO thin films for photovoltaic applications- February 2011
SO Klemm, SE Pust, AW Hassel, J Hüpkes and Karl J. J. Mayrhofer – Journal of Solid State Electrochemistry
The processes during chemical and electrochemical etching of Al-doped ZnO are investigated utilizing a scanning flow cell setup with online detection of dissolved Zn ions. The rate of chemical dissolution was found to be a linear function of buffer and proton concentration in near neutral pH solutions according to a transport limited reaction. In contrast, electrochemical etching is limited by the kinetics of the reaction and increases linearly with the imposed current density. Due to this fundamental difference, the dissolution of Zn can be either uniform over the whole surface or highly localized at active sites like grain boundaries. A combined approach of chemical etching and the well-controllable galvanostatic dissolution thus allows a fine adjustment of the ZnO:Al surface texture for applications in silicon thin film photovoltaic cells in order to improve their overall energy conversion efficiency. … A tungsten halogen lamp and the detector (EPP 2000, StellarNet, USA) were connected using 300 μm optical fibers. The absorption at 580 nm was measured once every 1.2 s and transformed into a concentration using the proportionality factor as…
