Development of new type sensor structures using epitaxial-thin-film growth technology

市面上有两种类型的气体传感器。一种是吸附型气体传感器，采用烧结的细颗粒气敏半导体氧化物等多孔结构。另一种是由烧结氧化物固体电解质组成的扩散型气体传感器。我们将外延薄膜生长技术应用到新型气体传感器结构中。对于气体吸附型传感器，将外延薄膜应用于气体传感器结构中，在较低浓度的目标气体下具有优异的传感能力，提高了响应时间。采用脉冲激光沉积（PLD）技术，在Y2O3掺杂的ZrO衬底上引入zfe （ZFO）同质外延缓冲层，制备了掺杂Zn铁氧体（ZFTO）外延薄膜。同质外延ZFTO/ZFO/YSZ薄膜的电导率高于异质外延ZFTO/YSZ薄膜。ZFTO薄膜的电阻率随NO22气体浓度的变化而变化。ZFTO薄膜的灵敏度随膜厚和NO气体浓度的变化而变化。ZFTO薄膜厚度为3 nm时灵敏度最高。在10- 23atm的O分压下，沉积在SrTiO23单晶衬底上的Cr掺杂SrTiO23外延薄膜仍具有较高的灵敏度。在气体扩散型气体传感器，Y掺杂ZrO232膜厚度为2.5 nm的情况下，Cr掺杂SrTiOIn的灵敏度达到最大。在（100）Si衬底上沉积（YSZ）外延薄膜。该薄膜不含妨碍氧化离子扩散的晶界。薄膜厚度较烧结体薄，降低了内部电阻率。利用YSZ外延膜和多孔Pt电极，在350℃下得到了计算的emf值。交流阻抗测试表明，在150La0.6Sr0.4Co0.98Ni0.02 O （LSCNO）电极下，YSZ薄膜中的氧化离子扩散到YSZ外延膜，降低了180℃下的工作温度

There are commercially available two types of gas sensors. One is the adsorption type gas sensor that isporous structure with sintered fine particles of gas sensitive semiconductor oxide. The other is thediffusion type gas sensor that is composed of the sintered oxide solid electrolyte. We apply epitaxialthin film growth technology into the new type gas sensor structures. In case of gas adsorption type sensor, applying the epitaxial thin film to the gas sensor structure bringsthe excellent sensing ability at lower concentration of the target gas and improved the response time. Tidoped Zn ferrite (ZFTO) epitaxial films were deposited on Y2O3 doped ZrO substrate by introducing Znferrite (ZFO) homo-epitaxial buffer layer using pulsed laser deposition (PLD). Homo-epitaxialZFTO/ZFO/YSZ films showed higher conductivity then hetero-epitaxial ZFTO/YSZ films. Resistivityof the homo-epitaxial ZFTO films changed with NO22 gas concentration. Sensitivity of the ZFTO filmswere changed with film thickness and NO gas concentration. The maximum sensitivity was obtained atthe 3 nm of ZFTO film thickness. The Cr doped SrTiO23 epitaxial thin film deposited on the SrTiOsingle crystal substrate showed high sensitivity even at 10-23 atm of O partial pressure. The maximumsensitivity was obtained at the 2.5 nm of Cr doped SrTiOIn case of gas diffusion type gas sensor, Y doped ZrO232 film thickness. (YSZ) epitaxial thin film was deposited on (100)Si substrate. This film did not contain the grain boundary which disturbs the oxide ion diffusion. Thethinner film thickness compared with sintered body reduced the internal resistivity. The calculated EMFvalue was obtained at 350oC using YSZ epitaxial film on Si with porous Pt electrode. AC impedancemeasurement revealed the oxide ion in the YSZ thin film diffused at 150La0.6Sr0.4Co0.98Ni0.02 O (LSCNO) electrode to YSZ epitaxial film reduces the working temperature at180℃