Study of the growth time effect on the structural, morphological and electrical characteristics of ZnO/p-Si heterojunction diodes grown by sol-gel assisted chemical bath deposition method

Well-aligned ZnO nanorods (NRs) have been synthesized by chemical bath deposition (CBD) method on (100) p-type Silicon substrate for various growth times. ZnO seed layers have been pre-coated on Si by sol-gel spin-coating process. The effect of growth time on structural, morphological and electrical properties of ZnO NRs were systematically investigated by X-Ray diffraction, scanning electron microscopy and current-voltage measurements at room temperature. SEM images illustrated that vertical, well-aligned, uniformly distributed, dense ZnO NRs were observed to grow on the Si substrate. Moreover, the growth rate decreases dramatically as the deposition time increased. X-ray diffraction pattern showed that the synthesized ZnO NRs have hexagonal wurtzite structure and exhibit a preferred orientation along the c-axis. The current–voltage analysis provided information about electrical parameters of n-ZnO NRs/p-Si heterojunction diode as a function of the growth time. The results showed an increase in the barrier height ϕ_b and a decrease in the ideality factor n, as the length of the NRs increased. More details about I–V characteristics measured under illumination and in the dark are also reported.