Fig. 2

XRD, FE-SEM, EDX, and morphology-dependent I-V curves. a 2θ scan XRD pattern of the ZnO NRs grown at 25 mM in ZnO NR-based NUV PDs, b (i) EDX spectrum of the selectively grown ZnO NRs on the active channel and their corresponding (ii) Zn, (iii) O, and (iv) Si elemental mapping images, and c I-V curves of the ZnO NR-based NUV PDs at (i) 15 mM, (ii) 25 mM, and (iii) 50 mM under dark state and illumination of 380 nm light. The photograph of a shows the top-view FE-SEM image of the ZnO NR-based NUV PD. The inset of c shows the cross-sectional FE-SEM images of the ZnO NRs grown at different concentrations of 15, 25, and 50 mM