Interconnected SnO2 Microsphere Films with Improved Ultraviolet Photodetector Properties

Metal oxide nanostructure detectors must adsorb both oxygen molecules and incident light to achieve ultrahigh photogain. However, the oxygen adsorption and desorption process can prolong the photoresponse time of the photogain. Therefore, it is a challenge to fabricate such metal oxide nanostructures that have the ability to adsorb both oxygen molecules and incident light simultaneously to generate large amounts of carriers under light illumination, using a simple preparation method. In this work, self-connected core-shell SnO2 microspheres were prepared and used as a photodetector. The interconnected SnO2 device exhibited improved photoresponse properties with photocurrent of 15.4 mu A at room temperature, representing a nearly 43-fold enhancement compared with traditional photodetectors. The underlying mechanism for this process was revealed by Hall mobility versus temperature and photocurrent versus power intensity characteristics. We found that conducting channels among the tightly interconnected microspheres are mainly responsible for the improved photocurrent response, providing effective paths for electron transport as well as available sites for charge carrier accumulation.