Influence of laser texturization surface and atomic layer deposition on optical properties of polycrystalline silicon

Abstract

Reducing the reflectance of light as a result of texturing the front surface of the silicon and depositing an antireflection coating allows to increase the efficiency of the solar cell by up to several percent. In the present paper, the surface texturing of polycrystalline silicon based on the laser treatment and Al2O3 antireflection coating (ARC) deposited by atomic layer deposition ALD is discussed. Polycrystalline silicon wafers are characterized by their different grain sizes and orientation (grains are randomly oriented). Much effort has recently been devoted to the development of techniques for creating more isotropic textures further reducing the reflectance of polycrystalline wafers. Therefore in the present work polycrystalline silicon surface was shaped with a laser beam. In order to further reduce the reflectance of light R(λ) to the surface of the solar cell Al2O3 antireflection coating was deposited by ALD method. Al2O3 thin film in the structure of finished solar cell functions as both an antireflection and the passivation coating, which simplifies the process. A unique advantage of ALD method is the ability to uniformly deposition on geometrically complex surfaces. For this reason, atomic layer deposition method may be used for deposition of the optical thin film on the silicon solar cells as antireflection coating. There are many methods of optical thin films, for example, sol–gel, CVD, PVD but with the advantage of ALD, earlier mentioned, seems to be the most promising.