Fabrication of Sol-Gel derived Antireflective Thin Films of $SiO_2-ZrO_2$ System

솔-젤법에 의한 $SiO_2-ZrO_2$계 무반사 박막의 제조

  • Kim, Byong-Ho (Dept. of Materials Science and Eng., Korea University) ;
  • Hong, Kwon (Dept. of Materials Science and Eng., Korea University) ;
  • Namkung, Jang (Dept. of Materials Science and Eng., Korea University)
  • 김병호 (고려대학교 재료공학과) ;
  • 홍권 (고려대학교 재료공학과) ;
  • 남궁장 (고려대학교 재료공학과)
  • Published : 1995.05.01

Abstract

In order to reduce reflectance of soda-lime glass having average reflectance of 7.35% and refractive index of 1.53, single (SiO2), double (SiO2/20SiO2-80ZrO2), and triple (SiO2/ZrO2/75SiO2-25ZrO2) layers were designed and fabricated on the glass substrate by Sol-Gel method. Stble sols of SiO2-ZrO2 binary system for antireflective (AR) coatings were synthesized with tetraethyl orthosilicate (TEOS) and zirconium n-butoxide as precursors and ethylacetoacetate (EAcAc) as a chelating agent in an atmosphere environment. Films were deposited on soda-lime glass at the withdrawal rates of 3~11 cm/min using the prepared polymeric sols by dip-coating and they were heat-treated at 45$0^{\circ}C$ for 10 min to obtain homogeneous, amorphous and crack-free films. In case of SiO2-ZrO2 binary system, refractive index of film increased with an increase of ZrO2 mol%. Designed optical constant of films could be obtained through varying the withdrawal rate. In the visible region (380~780nm), reflectance was measured with UV/VIS/NIR Spectrophotometer. Average reflectances of the prepared single-layer [SiO2 (n=1.46, t=103nm)], double-layer [SiO2 (n=1.46, t=1-4nm)/20SiO2-80ZrO2 (n=1.81, t=82nm)], and triple-layer [SiO2 (n=1.46, t=104nm)/ZrO2 (n=1.90, t=80nm)/75SiO2-25ZrO2 (n=1.61, t=94 nm)] were 4.74%, 0.75% and 0.38%, respectively.

Keywords

Sol-gel;Antireflective film;$SiO_2-ZrO_2$ system;Optical thickness design

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