ZINC OXIDE NANOWIRE-BASED MULTIFUNCTIONAL DEVICES

Abstract

This thesis tackles a significant gap in nanotechnology by developing a multifunctional ZnO nanowire-embedded MIS capacitor capable of UV photodetection, non-volatile memory, and pressure sensing within a single device. While ZnO nanowires are recognized for their individual applications, there is limited research on integrating multiple functions into one device. This work demonstrates a straightforward, scalable fabrication approach using randomly dispersed ZnO nanowire networks, offering a low-cost alternative to complex aligned nanowire methods, and making large-area production feasible for industrial applications.
The challenge of understanding charge transport in random nanowire networks—more complex than in aligned configurations—was addressed using percolation theory and Monte Carlo simulations. By establishing a universal scaling function, this approach links computational and experimental analyses, enabling a reliable model of network conductivity. Experimental validation revealed that tunnelling conduction dominates below the percolation threshold, providing crucial insight into charge transport behaviour.
Optimised at 4 wt.% ZnO concentration, this device prototype uniquely combines UV photodetection, pressure sensing, and non-volatile memory within a single MOS configuration, with each functionality capable of operating independently or simultaneously within the same device. For UV sensing, it achieves fast response times and high sensitivity; in pressure sensing, it offers reliable, scalable capacitive response; and as a memory device, it demonstrates stable and large memory window, repeatable performance. By delivering all these capabilities in one assembly, this work advances multifunctional nanowire-based technology, positioning ZnO nanowire networks as a promising solution for versatile, large-area electronic and optoelectronic applications.