Environmental Engineering Reference
In-Depth Information
4.3 Key Observations That Led to the Formulation of a
New Model
This section summarises the key experimental observations which
led to the formation of the new device concept for CdS/CdTe solar
cells.
4.3.1
Surface Modification of CdTe
Previous reports on work on crystalline CdTe have shown that it is
possible to modify the stoichiometry of the CdTe surface drastically
by chemical etching [9, 10]. Acidic solutions preferentially remove
Cd from the CdTe surface, leaving a Te-rich surface, and alkaline
solutions preferentially remove Te from the surface, leaving a Cd-
rich surface [9, 10]. This was revealed by X-ray photoelectron
spectroscopy (XPS), as shown in Fig. 4.3.
Figure 4.3
XPS spectra showing the possibility of producing (a) Te-rich
and (c) Cd-rich CdTe layers by chemical etching in acidic and alkaline
solutions, respectively [10].
