Ni-interlayer-induced modulation of electrical and dielectric properties in ZnO/Ni/ZnO thin films fabricated using hybrid deposition techniques

Interface engineering in oxide multilayers provides a powerful pathway to regulate charge transport and dielectric response in low-dimensional material systems. Here, ZnO/Ni/ZnO (ZNZ) trilayer thin films with fixed ZnO thickness and systematically varied Ni interlayer thickness are fabricated using a hybrid combination of atomic layer deposition (ALD) and direct current magnetron sputtering (DCMS). Structural analyses confirm the formation of well-defined multilayer architectures with thickness-dependent interfacial modification. Broadband alternating current (AC) electrical measurements reveal a pronounced frequency-dependent increase in conductivity, strongly governed by the Ni interlayer thickness. Analysis of the frequency exponent indicates that correlated barrier hopping is the dominant transport mechanism, demonstrating that charge transport is mediated by Ni-modified interfacial potential barriers rather than bulk conduction. Increasing Ni thickness results in higher barrier heights and lower activation energies, indicating more efficient interfacial hopping pathways. The dielectric constant, dielectric loss, and loss tangent decrease with frequency while increasing with temperature, consistent with thermally activated dielectric relaxation dominated by interfacial polarization effects. These findings establish metallic interlayer thickness as an effective control parameter for tuning charge dynamics and dielectric behavior in ZnO-based multilayers, highlighting the potential of interface-driven design strategies for advanced electronic, capacitive, and energy-storage applications.