Properties of Double-Layer Antireflection Al2O3/TiO2 Coatings by Liquid Phase Deposition

[[abstract]]In this investigation, aluminium oxide (Al2O3)/titanium oxide (TiO2) double-layer antireflection coatings (ARCs) were deposited on silicon substrate by liquid phase deposition (LPD). The deposition solution of ammonium hexafluoro-titanate and boric acid were used for titanium oxide deposition. Aluminium sulphate and sodium bicarbonate were used for aluminium oxide deposition. The concentration of the boric acid and sodium bicarbonate in the deposition solution controls the rate of deposition of titanium oxide film and aluminium oxide film. In the optimum condition, the refractive index of LPD-TiO2 and LPD-Al2O3 were 1.87 and 1.57, respectively. The average reflectance was 2.2 % at wavelengths from 400 to 800 nm under the thickness of the LPD-TiO2 and LPD-Al2O3 of 157 nm and 157 nm. This anti-reflective property is comparable to other vacuum deposition method, such as PECVD and sputtering, which makes the LPD-ARC film be very favorable for Si-based solar cells