The dielectric characteristics of spray deposited α-Si3N4:ZnO thin films: The nitride effect on frequency-dependent capacitance and conductance profiles

Abstract

The study focused on the effect of α-Si₃N₄ doping on the electrical/dielectric properties of ZnO thin films. Both α-Si₃N₄ doped and additive-free ZnO thin films were coated on p-Si substrates via a spray deposition method to achieve this. The electrical (current density (J)-voltage (V)) and dielectric properties (capacitance (C), conductance (G), dielectric loss (tanδ), reel/imaginary part of dielectric permittivity (ε′ and ε″) and electric modulus (M′ and M″)) were determined for all samples by using dielectric spectroscopy (DS) method. On the other hand, scanning electron microscopy (FESEM) and energy-dispersive spectroscopy (EDS) analysis were performed to evaluate microstructure, X-ray diffraction (XRD) was used to define chemical composition and atomic-force microscopy (AFM) analysis was carried out to characterise the topology of the coating layers. The thickness/surface roughness was obtained as ∼82.5 nm/10.6 nm for undoped and ̴ 99.5 nm/10.4 nm for nitride-doped samples, respectively. The maximum capacitance value (C) was obtained as 275 pF at −3.0V and 200 Hz, and the optimal conductance (G) value was also found as 45 μS around 4.0V and 1 MHz in the nitride-doped sample. The average of α and τ values was calculated as 5.67 × 10⁻⁵ s, 0.146 and 4.49 × 10⁻⁵ s, 0.081 for nitride-doped and undoped ZnO, respectively. The increase in performance can be attributed to the homogeneous and almost equally-size distribution of the ZnO grain growth which is strongly controlled by α-Si₃N_4.