| 摘要 |
PURPOSE:To obtain a reflection preventing film made of multi-layer of thin films by a method wherein a substrate on which a photo-electromotive force junction plain formed is immersed in two kinds of solution which contains the 1st and the 2nd metal respectively and is lifted up at a required speed and is treated by heat at a temperature not less than 300 deg.C. CONSTITUTION:An Si substrate which has a photo-electromotive force junction plain is immersed in a solution of ethanol and acetic acid which contains 3.4% Ti(OC4H9)4 and is lifted up at a speed of approximately 2.5mm./sec., so that the substrate is covered by a thin film of TiO2. The substrate is then treated by heat in an atmosphere at a temperature not less than 500 deg.C. Then the substrate is immersed in a solution of methanol and ethanol which contains 6% Al(NO3)3 and is covered by a thin film of Al2O3 by the same process. If the heat treatment temperature is less than 300 deg.C the formed film will dissolve into the immersed solution and if it is more than 1,100 deg.C a silver electrode will melt. The thickness of each thin film of the reflection preventing film is determined by the lifting speed and the solute density in the solution. The film thickness d which makes the reflectance minimum when a wavelength lambda0 is nealy 500nm is calculated by a formula nd=lambda0/4, where n is a refractive index, and d is obtained in d=550-800Angstrom . With the above configulation, the TiO2-Al2O3 constituted double- layered reflection preventing film can be formed uniformly, easily and at low cost. |
