Abstract
Thermal annealing is recognized as an effective tool to manage the structural and electronic properties of oxide thin films. Combined with the atmospheric environment control, additional issues concerning surface effects act to change the performance of oxides for photodetectors purposes. The present investigation systematically studies morphological and optical properties and electrical transport of CdO thin films using an as-grown reference and annealed samples at 500 °C under O2 and N2 atmospheres. As-grown CdO presents fast and high photoresponses in a wide range of the visible spectrum, with an amplitude that reaches nearly 3000%. Also, a transition from negative to positive photoresistance was observed for temperatures below 230 K. From the analysis of the photoluminescence spectra, we noted two activation energies for as-grown CdO, whereas annealed samples presented only one. Therefore, the additional defect level, reduced after annealing, is responsible for the huge amplitude as well as the negative to positive transition in the photoresistance of as-grown CdO film.
Published Version
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