RESUMEN

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.

Asunto(s)

RESUMEN

In this work, UV light activated multi-cycle photoelectric properties of TiO2 and CdS/TiO2 films in formaldehyde were researched. TiO2 film was prepared by screen printing, CdS/TiO2 compounded film was synthesized by SILAR method. XRD and FE-SEM was used to characterize the TiO2 and CdS/TiO2 samples. Multi-cycle photoelectric properties of TiO2 and CdS/TiO2 with uv light on and off were evaluated by testing the photocurrent. On one hand, under the same bias voltage, CdS/TiO 2showed a higher photocurrent than that by TiO2. The reason for this result should be ascribed to the compounded structure in CdS/TiO2, with which the separation and transfer of photogenerated electron-hole pairs could be improved. On the other hand, with the testing cycle number increased, the photocurrent amplitudes of TiO2 and CdS/TiO2 increased. These results suggested that the time to reach a stable photocurrent value for TiO2 and CdS/TiO2 is much longer than one cycle time (300 S). To illustrate the increased photocurrent amplitude value cycle by cycle, the photocurrent of CdS/TiO2 to a much longer time (more than 4000 seconds) was also tested. To explain these results, corresponding possible illustrations were presented.