Oxygen Sensing Properties of SrTiO₃ Thin Films

Abstract

The oxygen sensing properties of SrTiO 3 -based thin films have been investigated at room temperature. First, nondoped SrTiO 3 was investigated. Although such a material is highly sensitive, its electrical resistance was too high and not feasible for practical use. Donor (Nb 5þ ) could lower the resistance of SrTiO 3 ; however, the sensitivity was lost. UV-light irradiation or t 2 -type acceptor (Cr 3þ ) doping could lower the resistance and yet maintain the sensitivity. In contrast to t 2 -type acceptor doping, e-type acceptor (Fe 3þ ) doping could lower the resistance; however, the sensitivity was lost. In this paper, we discuss the phenomena from the viewpoint of polaron-controlled carrier conduction.

Effect of crystallization on the band structure and photoelectric property of SrTiO3 sol–gel derived thin film

“…Being one of the most typical materials, SrTiO 3 (STO) has been extensively investigated as oxygen-sensing materials [1,2] and superconducting substrate materials [3] owing to its unique properties. In addition, STO as a stable n-type semiconductor material has extensive applications in photoelectrochemical (PEC) water splitting [4] and photocatalytic degradation of organic compounds [5].…”

Doping effect of Dy on leakage current and oxygen sensing property of SrTiO3 thin film prepared by PLD

“…Detailed measurement conditions were described in our previous paper. 17) In this work, the resistance of the films was measured at room temperature both in air and in He atmosphere, then the sensitivity was calculated as the difference of resistance (R(in air)-R(in He)). The crystal structure of the films was measured using an X-ray diffraction (Rint 2200, Rigaku Co.).…”

“…4, 5 and 6, it can be mentioned that the sensitivity for an oxygen gas is closely related to the leakage current, and to improve the oxygen sensitivity, it is important to suppress the leakage current. Hara et al 17) examined the effect of Nb-doping into a SrTiO3 thin film on the oxygen sensitivity, and they found that the sensitivity decreases by a carrier doping. The result of the Dy-doping agrees well with the report.…”

“…As p-type oxygen sensors, Mg-doped SrTiO3 13), 14) and Fe-doped SrTiO3 15), 16) have been reported and as a n-type sensor, SrTiO3 without dopant 17) has been reported. In an n-type semiconductor, the resistivity decreases with decreasing an oxygen partial pressure, and in a p-type semiconductor, the resistivity increases with decreasing an oxygen partial pressure.…”

“…For an n-type SrTiO3 thin film, it has been shown that a control of the resistance is important for an oxygen gas sensitivity, and the sample having low resistance does not show the oxygen sensing properties. 17) This suggests that the control of the carrier concentration is important.…”