Fig. 3

a The length-dependent recombination rate of ZnO NWs with a diameter of 50 \({\text{nm}}\) we obtain from the model. Inset: the recombination rate \(\tau^{ - 1}\) and the recombination rate per unit area \(\tau_{p}^{ - 1}\) are calculated from the experimental data in Ref. [32]. b Comparison of the results calculated in this work with the experimental and calculation ones in Ref. [4]. Under a voltage of 10 V, the photocurrent as the function of the height of ZnO NWs with a diameter of 50 nm