November 22, 2013 / Polycrystalline silicon solar cell inspection using confocal Raman microscopy

Close Menu
 


November 22, 2013 / Polycrystalline silicon solar cell inspection using confocal Raman microscopy

Polycrystalline silicon solar cell inspection using confocal Raman microscopy

 

3D Scanning Laser Raman Confocal Microscope

Interdisciplinary Research
at the sub-micrometer range

  • Confocal Raman / fluorescence microscopy
  • Compact modular system
  • Wide spectral range (UV,VIS, IR)
  • High sensitivity
  • High temporal and thermal stability

 

Energy from renewable sources, solar energy for example, is expected to play the important role in the near future. To convert the energy of sunlight directly into electricity, silicon solar cells (crystalline or polycrystalline) are widely used, because silicon technology is dominated in the market due to quickly reducing cost. Poly-Si cells are cheaper than single crystal, but they are less efficient. Polycrystalline cells are made from large blocks of molten and solidified silicon. Microscope optical image of such type of cell is done in Fig.1. Blocks of different types of Silicon can be observed on this optical image. The presence of non-crystalline silicon leads to reduced conversion efficiency, and due to this, testing crystallinity of silicon in solar cells is important for the manufacture process. Raman spectroscopy can be used for analyses of crystallinity. This application note demonstrates it on the example of a polycrystalline silicon solar cell (Fig.2)

 

In crystalline silicon the bond lengths are uniform, and as a result there is only one sharp peak at 520 cm-1. In amorphous silicon the bond lengths are varied leading to broad diffuse spectral features around 480cm-1 (Fig.2). The crystalline fraction is proportional to the intensity ratio of I520/I480. It is possible to see from Fig.2, that different blocks on the polycrystalline silicon cell have different amount of amorphouse phase.

 

Summary

We have demonstrated that Confotec MR520 can be used for silicon solar cell inspection using confocal Raman microscopy.

 

 

 

 

 

 SOL instruments: спектрометр, рамановский микроскоп, эмиссионный спектрометр. confotec mr520 sait 800

Figure 1

SOL instruments: спектрометр, рамановский микроскоп, эмиссионный спектрометр. pv fig1

Microscope optical image of polycrystalline silicon solar cell. Large blocks of molten and solidified silicon can be observed on this image.

Figure 2

SOL instruments: спектрометр, рамановский микроскоп, эмиссионный спектрометр. pv fig2
Raman imaging of Polycrystalline silicon solar cell.
Black color corresponds to a higher content
of Si crystalline fraction, and bright colors correspond
to the raised contents of amorphous phase.