Enhanced photocurrent gain by CdTe quantum dot modified ZnO nanowire

• A micro scale photodetector fabricated using ZnO nanowires with high photocurrent gain was developed using dielectrophoresis technique.
• The photocurrent gain was enhanced more than 10 times after decorating the ZnO nanowires with CdTe quantum dots.
• The enhanced photocurrent gain was attributed to the high efficiency charge transfer between the ZnO nanowires and CdTe quantum dots.

In this paper, a zinc oxide (ZnO) nanowire (NW) photodetector was fabricated using dielectrophoresis technique. The ZnO NW was synthesized by chemical vapor deposition (CVD) method, and characterized by SEM, XRD and photoluminescence (PL) spectrum. The photodetector showed obvious photoresponse to 365 nm UV light. By decorating the ZnO NWs with CdTe quantum dots (QDs), the photocurrent (PC) gain was enhanced from 199 to 2896, when the light intensity was 5.3 mW/cm2. The response spectrum was also extended to the visible light region. The underlying mechanism of the enhancement was assigned to the high-efficiency charge transfer caused by the type-II band structure between ZnO NWs and CdTe QDs. The greatly quenched PL intensity of CdTe QDs/ZnO NWs composites provided further evidence for the high efficiency charge transfer.