Application of mesoporous TiO2 as a thermal isolation layer for infrared sensors

An ordered, mesoporous TiO2 thin film could possibly enhance the efficiency of a microbolometer when used as a thermal isolation layer. The infrared transmission characteristics of a 150 nm thick mesoporous TiO2 film were measured by FT-IR. The calculated infrared absorption rate was higher than 85% in the 8-12 mu m wavelength region. The thermal conductivity of a mesoporous TiO2 film was measured by the 3 omega method. The CFD-ACE program was used to simulate the thermal isolation effect of a mesoporous TiO2 film inserted in a microbolometer structure. The simulation shows that a great enhancement in the thermal insulation was obtained by using a mesoporous TiO2 layer. The mesoporous TiO2 thin film effectively blocks heat flow from TiN absorber to the bottom layer and returns the downstream heat to the upper resistor layer. (C) 2007 Elsevier B.V. All rights reserved.