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Silicon Based PV Cells

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CHAPTER 2 – SILICON BASED PV CELLS 2 2.1 Doping Procedure of Silicon based PV Cells A Silicon solar PV Cell is a device which is made up of semiconductor materials that produce electricity when exposed to light energy. [1] The doping process of a Silicon based PV Cell works by the photovoltaic material converting the light energy, photons, it absorbs into electrical energy. [1] Light (Photon) Energy ------- Electrical Energy Using a doping process, a p-n junction is created in silicon as shown below: From the image above the photons, light energy, prompt the electrons flowing from the n-junction to the p-junction creating an electric current flow. [1] This is highlighted below: The process of doping involves the addition of atoms with different number of electrons so it creates an unbalanced number of electrons on the material that is being doped, in this case Silicon. [1] The material being doped, in this case Silicon will carry a negative charge if the base material absorbs excessive electrons. However, if the base material, Silicon, absorbs to little electrons then the material will carry a positive charge. [1] To achieve a doped material, using Silicon then there are 2 methods: Ion implantation of diffusion. These methods are carried out using Boron (B) to form a positively charged doped material and Arsenide (As) or Phosphorus (P) to form a negatively charged doped material. This is shown below: Ion Implantation can be achieved at room temperature for

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