In this work, a comparative performance analysis of ZnO nanowires grown by following single- and double-step techniques on (100) p-Si substrate has been conducted. High-quality ZnO nanowires with c-axis orientation and perfect crystalline structures with appropriate chemical stoichiometry have been obtained from both the approaches. The areal density of the nanowires grown from double step approach is almost twice the nanowires grown by employing the single step approach. Histogram analysis shows that the diameter and height of majority of the single-step grown nanowires are ~370nm and ~2.45µm, and for the double step grown nanowires these are ~210 nm and ~2.16 µm, respectively. The bandgap values of the single-step and double-step grown nanowires are measured to 3.19eV and 3.26eV, respectively. The current-voltage characteristics of p-Si/n-ZnO diodes indicate that the forward current is contributed by both the electrons and holes and the relevant cut-in voltages are measured to be 0.5V and 2.5V, respectively.