We investigated the power-law responses in two types of tin dioxide (SnO₂) films: one made from nanosized grains and another from from very large grains, both under dry air. Experimental results revealed a significant dependence between the sensitivity and the SnO₂ grain size. We therefore propose, that the gas sensor sensitivity is not only determined by oxygen chemisorption, but also by changes in the density of oxygen vacancies in response to changes in the ambient gas pressure. Band bendings and adsorbate coverages for different oxygen pressures were derived resorting to the electroneutrality condition, including changes in the concentration of oxygen vacancies within the grains due to the exposure to different oxygen pressure. The consequences for the film conductivity and its power-law response were analyzed and compared with experimental results.

我们研究了两种类型的二氧化锡（SnO ₂）膜的幂律响应：一种是由纳米级颗粒制成，另一种是由非常大的颗粒制成，都在干燥的空气中进行。实验结果表明，灵敏度与SnO ₂之间存在显着相关性晶粒尺寸。因此，我们提出，气体传感器的灵敏度不仅取决于氧气的化学吸附，还取决于响应于环境气压变化的氧气空位密度的变化。根据电子中性条件，得出了不同氧压下的能带弯曲和吸附物覆盖率，包括由于暴露于不同的氧压下晶粒内氧空位浓度的变化。分析了对薄膜电导率及其幂律响应的影响，并与实验结果进行了比较。