Scanning electron microscop chemical etching

The effect of light trapping on solar cell performance is demonstrated by ZnO Al films with different surface textures. Figure 8.8 shows scanning electron microscope (SEM) images of these ZnO Al films. Sputtered ZnO Al is initially smooth (Fig. 8.8a). By a simple wet-chemical etching step in diluted hydrochloric acid (typically 0.5% HC1) one can roughen the ZnO Al surface which is shown after a short dip (Fig. 8.8b) and after an optimized etch... 

In addition small-scale exposures at 870"C were used to study further the role of water vapour with 20 vol.-% and 30 vol.-% water vapour in air in an alumina tube furnace. Phase morphology was studied with scanning electron microscope (SEM). To distinguish between the glassy and crystalline phases some samples were etched in 2-% HF-solution. Phase composition was determined by a quantitative X-ray diffraction (XRD) analysis based on the internal standard, Cap2, method. The chemical composition of the amorphous phase in the binder was determined locally with EDS analysis in SEM. A bulk chemical analysis of the amorphous phases in binder was performed by Induction Coupled Plasma Mass-Spectrometry (ICP-MS). The samples were crushed powders of as-received and 500 h at water vapour bulk exposed (w) materials. The glassy phase was dissolved in HF-HNO3 solution. Open porosity, apparent and bulk densities of each specimen were determined by Archimedes method before and after the tests. 

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