Investigation of frequency-dependent dielectric properties of ZnO nanorods grown on Si wafer: In/ZnO/p-Si heterostructure

We report the result of an in-depth study of growth, structural properties and frequency-dependent dielectric function of ZnO nanorods (NRs) grown on p-Si as well as the In/ZnO/p-Si heterostructures. The NRs were produced by hydrothermal method on the Si substrate in a Teflon-lined stainless-steel cover at 90°C. Scanning electron microscopy analysis indicates nanorod morphology while LeBail refinement of XRD data showed that the ZnO NRs crystallize in hexagonal wurtzile structure with (002) orientation (space group P63mc). The dielectric properties of the In/ZnO/p-Si heterostructure were calculated with the help of experimental admittance measurements performed in the ± 5 V voltage range and 1 kHz/1 MHz frequency range under ambient conditions. The real part of the complex relative permittivity (ε′), the imaginary part of complex relative permittivity (ε″) and loss tangent (tanδ) were obtained. Also, real (M′) and imaginary (M″) parts of the complex electric modulus (M*) were extracted. Frequency dependence in the ε′, ε″ and tanδ was attributed to the frequency dependence of the space charge polarization. The real part of electrical modulus was found to be nearly independent of frequency and voltage for positive voltages.