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The Thermo Scientific ELEMENT GD high-resolution glow discharge mass spectrometer has been readily accepted by the solar cell industry for purity control of the Silicon base material.
The combination of simple sample preparation, a short analysis time, and ppb detection limits for bulk Si make this instrument a valuable tool for demanding production control
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Incoming Si chunks are simply ground to achieve a flat surface, washed with dilute nitric acid and water, and finally blown dry before introduction into the GD-MS. A complete elemental analysis, including presputtering of the sample surface, can be made in 20 minutes. Through the use of high mass resolution matrix-related polyatomic interferences are separated from the analyte elements. As an example, Figure 1 shows the unambiguous detection of 56Fe despite the presence of more abundant interferences (28Si2 and 40Ar16O) at higher masses.
| An estimate of the technique’s detection capabilities was obtained from repeat analysis of high purity Silicon samples at 5 different spots. Typical detection limits obtained with the ELEMENT GD (see Table) are at or below the single digit ppb level. All concentrations obtained are semi-quantitative as no reference materials are available for calibration. Nevertheless, the relative variation between samples will be accurate, therefore providing a valuable tool for production and contamination control in the solar cell industry. |
click to enlarge |
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| Element |
Mass |
Average
n = 5 spots
conc [ppb] |
LoD (3s)
n = 5 spots
conc [ppb] |
| B |
11 |
2.8 |
1.3 |
| Na |
23 |
0.6 |
0.4 |
| Mg |
24 |
0.08 |
0.05 |
| Al |
27 |
0.8 |
0.6 |
| P |
31 |
16 |
7 |
| Ca |
44 |
< LoD |
2.3 |
| Cr |
52 |
0.21 |
0.15 |
| Mn |
55 |
< LoD |
0.06 |
| Fe |
56 |
< LoD |
0.5 |
| Ni |
58 |
< LoD |
0.3 |
| Co |
59 |
0.4 |
0.1 |
| Cu |
63 |
0.5 |
0.2 |
| Zn |
64 |
3.7 |
0.5 |
| Ge |
72 |
< LoD |
1.5 |
| As |
75 |
0.4 |
0.3 |
| Zr |
90 |
< LoD |
0.11 |
| Ag |
107 |
< LoD |
0.2 |
| Sn |
118 |
< LoD |
0.5 |
| Sb |
123 |
< LoD |
0.3 |
| Au |
197 |
< LoD |
0.3 |
| Pb |
208 |
0.09 |
0.08 |
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1 Articles Total 995.00 USD 
