Observing the optical transitions in Tin Oxide at room temperature is a difficult task because of its forbidden bandgap nature in bulk form. Moreover, it possesses the well know low emission efficiency issue in its reduced dimensional thin film structures. In this work, we use Electroreflectance (ER) method to recover the optical transitions in tin oxide thin films. A metal-oxide-metal geometry, with SnO2 film was sandwiched between two metal electrodes, was illuminated by the light under an external perturbation voltage. This results the well-enhanced critical points in the ER spectra with a suppressed featureless background. The characteristics of observed critical points are found using the third derivative functional form model. The points are identified as defect transition and surface exciton transition originated due to the presence of defect states formed by the oxygen vacancies. In addition to this, the free exciton transition, from deep of the valence band to the conduction band, is explicitly revealed by ER spectra of r-SnO₂ film. A built-in electric field driven by external voltage is supposed to be the main factor for enhancing the critical points associated with optical transitions.

在室温下观察氧化锡的光学跃迁是一项艰巨的任务，因为其块状形式的禁带性质。此外，它在其尺寸减小的薄膜结构中具有众所周知的低发射效率问题。在这项工作中，我们使用电反射 (ER) 方法来恢复氧化锡薄膜中的光学跃迁。金属-氧化物-金属几何结构，SnO2 薄膜夹在两个金属电极之间，在外部微扰电压下被光线照射。这导致 ER 光谱中的临界点得到了很好的增强，并且具有被抑制的无特征背景。使用三阶导数函数形式模型发现观察到的临界点的特征。由于氧空位形成的缺陷态的存在，这些点被识别为缺陷跃迁和表面激子跃迁。除此之外，从价带深处到导带的自由激子跃迁由 r-SnO 的 ER 光谱明确揭示₂电影。由外部电压驱动的内置电场被认为是增强与光学跃迁相关的临界点的主要因素。