Sonochemical Synthesis of a Zinc Oxide Core-Shell Nanorod Radial p-n Homojunction Ultraviolet Photodetector

ACS Appl Mater Interfaces. 2017 Jun 14;9(23):19791-19799. doi: 10.1021/acsami.7b02634. Epub 2017 May 31.


We report for the first time on the growth of a homogeneous radial p-n junction in the ZnO core-shell configuration with a p-doped ZnO nanoshell structure grown around a high-quality unintentionally n-doped ZnO nanorod using sonochemistry. The simultaneous decomposition of phosphorous (P), zinc (Zn), and oxygen (O) from their respective precursors during sonication allows for the successful incorporation of P atoms into the ZnO lattice. The as-formed p-n junction shows a rectifying current-voltage characteristic that is consistent with a p-n junction with a threshold voltage of 1.3 V and an ideality factor of 33. The concentration of doping was estimated to be NA = 6.7 × 1017 cm-3 on the p side from the capacitance-voltage measurements. The fabricated radial p-n junction demonstrated a record optical responsivity of 9.64 A/W and a noise equivalent power of 0.573 pW/√Hz under ultraviolet illumination, which is the highest for ZnO p-n junction devices.

Keywords: core−shell nanorods; doping; p:ZnO; photodetector; radial p−n junction; sonochemistry.