Schottky enabled enhanced UV detection by graphene oxide composited transparent ZnO thin films

Abstract

Transparent optoelectronics devices have recently drawn considerable research attentions for the next generation electronic technologies. Here, we fabricate highly transparent (87 to 90% under visible light) composite films of graphene oxide (GO) and zinc oxide (ZnO) by all-solution process. The non-linear current–voltage characteristics at room temperature resemble Schottky barrier junction formation between ZnO-GO film surface and Ag dot. Under UV irradiation (λ ~ 375 nm and power density ~1 mW/cm2) the ideality factor increases from 7.82 to 8.72 but the potential barrier height reduces from 0.66 to 0.50 eV in ZnO and ZnO-GO 25% films which are favorable for advancing optoelectronic technologies. This is demonstrated by excellent UV photoresponsivity of 5.3 A/W at low bias (+1 V) for ZnO-GO 25% along with low UV response (15.8 s) and recovery times (36.6 s). While at −1 V bias the photoresponsivity reaches to 1.25 A/W. Such distinct characteristics as compared to other reports on all-solution processed ZnO-GO composites could be attributed to the reduction of GO to form rGO within ZnO matrix to develop conducting channels in the composite films, the formation of excellent Schottky barriers with Ag, the modulation in excitonic characteristics by defect distributions at the interfacial regions among rGO flakes and ZnO matrix, and the facilitated charge transport through the junctions.