ZnO-core/ZnSe-shell nanowire UV photodetector

Abstract

ZnO–ZnSe core–shell nanowires were synthesized by the thermal evaporation of a mixture of ZnO and graphite powders and ZnSe powders sequentially. Subsequently, multiple networked ZnO–ZnSe core–shell nanowire photodetectors were fabricated. The diameters and thicknesses of the ZnO-core/ZnSe-shell nanowires ranged from 50 to 150 nm and from 15 to 25 nm, respectively, and the lengths of the nanowires ranged up to a few hundreds of micrometers. Our results showed that the photoconductivity and response time of the ZnO nanowires were enhanced significantly and reduced, respectively, by encapsulating them with a ZnSe thin film. Under a 2 V applied voltage, the dark current and photocurrent of the ZnO NW photodetector were 2.04 × 10−7 A and 9.94 × 10−6 A, respectively. In contrast, the dark current and photocurrent of the ZnO-core/ZnSe-shell nanowire photodetector were 7.50 × 10−8 A and 1.75 × 10−5 A, respectively. The rising and decaying times of the core–shell nanowires were 6.2 and 5.8 s, respectively, whereas both the rising and decaying times of the pristine ZnO nanowires were 7.3 s. The photoconduction mechanism in the core–shell nanowires is discussed.