Structure and Oxygen Sensing Properties of TiO_2 Porous Semiconductor Thin Films

摘要

Semiconductor-type TiO_2 oxygen sensing thin films were synthesized using tetrabutyl titan-ate (Ti(OBu)_4) as precursor and diethanolamine (DEA) as complexing agent by the sol-gel process. The porous and oxygen sensing TiO_2 films were obtained by the addition of polyethylene glycol (PEG). The micrographs of scanning electron microscope (SEM) show that the pores of the sample about 400—600 nm in size with PEG (2 000 g/mol) are larger than those about 300 nm in size with PEG(1 000 g/mol), while the density of pores is lower. The results also indicate that increasing the content of PEG properly is beneficial to the formation of porous structure. With the increasing content of PEG from 0 g to 2.5 g, the oxygen sensitivity increases from 330 to more than 1 000 at 800℃, from 170 to more than 1 000 at 900 ℃, and the response time to O_2 and H_2 are about 1.5 s and less than 1 s, respectively.