Anti-reflective coating formation on silicon - by chemical reaction vapour deposition to form oxide of niobium titanium, tantalum, zirconium, hafnium or yttrium

摘要

Method for applying an antireflecting coating to the light absorbing surface of a Si solar cell, comprises (a) heating the surface to above 325(325-450) deg.C; (b) directing onto the surface from separate sources, oxygen and a vapour of a metal halide and/or alcoholate together with a reducing gas, so that an antireflecting oxide of the metal forms on the Si surface. The metal is Nb, Ti, Ta, Zr, Y or Hf and the reducing gas is methanol, nitrogen, or forming gas. The method does not require the high vacua needed in the known vapour deposition processes, being effected at atmos. pressure. It is easier to control and requires less energy. Suitable halides are TaCl5, NbCl5, TiCl4, ZrCl4, YCl3 and HfCl4. Suitable alcoholates include Ta ethylate, Ti ethylate, Ti isopropylate, Zr isopropylate, Zr n-propylate, and Zr n-pentylate. The antireflecting layer produced is 550-650 angstroms thick.