The development of a pyroelectric thin-film infrared sensor by micro-opto-electro-mechanical system (MOEMS) technology

An infrared (IR) sensor with the lead-titanate (PbTiO3) thin-film and thermal isolation improvement structure using the technology of micro-opto -electro-mechanical systems (MOEMS) has been designed, fabricated and developed. In this paper, both numerical analysis of the static operation mechanism such as the effects of IR light power on the the depletion layer width and voltage drop across the thin PbTiO3 film, and the dynamic response of a thin-film pyroelectric sensor to sinusoidal modulated radiation are reported and compared to the experimental results. The fitting is quite well. The major IR-sensing part on the cantilever beam of the developed sensor consists of a 50-nm PbTiO3 layer deposited by RF sputtering, and a gold (Au) layer evaporated as an IR radiation absorber. With active cantilever dimensions of 200x100x5 mu m(3) formed by etching processes, the cantilever structure exhibits a much superior performances to that of a traditional IR-sensing bulk structure under the 800-mu W incident optical light with wavelength of 970 nm.