Atomic layer deposition of Al_(2)O_(3) and TiO_(2) multilayers for applications as bandpass filters and antireflection coatings

摘要

Al_(2)O_(3) and TiO_(2) thin films have been deposited on Si wafers, quartz, BK7 glass, and polycarbonate substrates by atomic layer deposition (ALD). The refractive indices and growth rates of the materials have been determined by spectroscopic ellipsometry and transmission electron microscopy. The influence of substrate temperature and precursor on the refractive indices has been investigated. The refractive index of TiO_(2) significantly increases with temperature, whereas the Al_(2)O_(3) films are temperature insensitive. The films deposited using H_(2)O_(2) as oxygen source show a slightly higher refractive index than the films prepared with H_(2)O. Multilayer narrow-bandpass filters and broadband antireflective coatings have been designed and produced by ALD.