Research on Photoelectric Responses of SnO₂ Film to Humidity Under UV Light Irradiation.

In this work, to research the photoelectric responses to humidity using a semiconductor film, an ultraviolet (UV) light induced device has been investigated on SnO₂ film at room temperature. Screen printing method was used to prepare SnO₂ film on the Al₂O₃ substrate. The crystalline structure and morphology of SnO₂ was characterized with XRD and FE-SEM. The UV light induced photoelectric responses of SnO₂ to a constant humidity (20% RH) were evaluated firstly under four different bias voltages. At 2 V bias voltage, the photocurrent amplitude reaches 4.58 μA, which is higher than that of 0.2 V bias (0.27 μA). Then the photoelectric responses to different relative humidity conditions (20% RH, 40% RH and 60% RH) were tested. The results display that the photocurrent decreased while the relative humidity increased. To illustrate the anomaly current of SnO₂ film at 60% RH, the darkcurrent to different relative humidity conditions (20% RH, 40% RH and 60% RH) were also tested. To make clear these results, corresponding probable illustration was proposed.