Enhanced Spectral Response of ZnO-Nanorod-Array-Based Ultraviolet Photodetectors by Alloying Non-Isovalent Cu-O with CuAlO 2 P-Type Layer.

CuAlO ₂ was synthesized by a hydrothermal method, in which the Cu-O dimers were incorporated by simply altering the ratio of the reactants and the temperature. The incorporation process increases the grain size in CuAlO ₂ , and modulates the work function and binding energies for CuAlO ₂ due to the partial substitution of Cu ⁺ 3d ¹⁰ with Cu ²⁺ 3d ⁹ orbitals in the valence band maximum by alloying non-isovalent Cu-O with a CuAlO ₂ host. Based on the ZnO nanorod arrays (NRs) ultraviolet photodetector, CuAlO ₂ /Cu-O fabricated by the low-cost drop-coating method was used as the p-type hole transport layer. The incorporation of the Cu-O clusters into CuAlO ₂ lattice to enhance the conductivity of CuAlO ₂ is an effective way for improving ZnO NRs/CuAlO ₂ device performance. The photodetectors exhibit significant diode behavior, with a rectification ratio approaching 30 at ±1 V, and a dark saturation current density 0.81 mA cm ^-2 . The responsivity of the ZnO-NRs-based UV photodetector increases from 13.2 to 91.3 mA/W at 0 V bias, with an increase in the detectivity from 2.35 × 10 ¹⁰ to 1.71 × 10 ¹¹ Jones. Furthermore, the ZnO NRs/[CuAlO ₂ /Cu-O] photodetector exhibits a maximum responsivity of 5002 mA/W at 1.5 V bias under 375 nm UV illumination.