Recent Progress on The Application of Spectroscopic Ellipsometry for a Multilayer Analysis of CdTe-Based Solar Cell Structures Incorporating Magnesium–Zinc Oxide Transparent Layers

We present some recent progress that has been made on the application of an optical function parameterization of polycrystalline Mg<i>x</i>Zn1-<i>x</i>O (MZO) thin films on the bandgap that has been used for the metrology of CdTe-based solar cell structures that incorporate MZO thin films as high resistivity transparent (HRT) layers. The acquired parametric expressions are applied to facilitate the mapping spectroscopic ellipsometry (M-SE) of device structures consisting of glass/SnO2:F/MZO. M-SE is shown to provide maps in the MZO effective thickness and bandgap within confidence limits of ± 1 nm and ± 0.003 eV, respectively. As a second application of this parameterization, performed on an as-deposited glass/SnO2:F/MZO/CdS/ CdTe device structure, has been made using through-the-glass spectroscopic ellipsometry (TG-SE). Such an analysis is also shown to provide the MZO effective thickness and bandgap. The outcome of the TG-SE analysis for this device structure enables simulations of the external quantum efficiency (EQE) spectrum of the resulting solar cell assuming different recombination losses within the individual layers of the structure. A comparison of these simulations with the experimental EQE spectrum reveals improved current collection from the front of the device incorporating an MZO HRT layer.