Temperature-dependent dielectric properties of p-n heterojunction diodes based on hydrothermally synthesized ZnO nanostructures

In this study, the effect of coating p-Si substrates with a pure ZnO layer using the hydrothermal reaction method on the dielectric parameters was reported. The studied dielectric properties of the ZnO/p-Si structure include dielectric constant (& epsilon;& PRIME;), dielectric loss (& epsilon;& DPRIME;), ac electrical conductivity (& sigma; AC), and real and imaginary electrical modulus (M & PRIME;, M & DPRIME;). These properties were investigated using experimental capacitance-frequency (C-f) and conductivity-frequency (G-f) measurements in a frequency range of 20 Hz-1 MHz and a temperature range of 300-420 K. Experimental results show that dielectric parameters are strongly frequency- and temperature-dependent. The dielectric constant showed an increase of about 11 times in the investigated temperature range. At the same time, AC electrical conductivity increased with increasing frequency and temperature. In addition, the electrical modulus was examined, and peaks were observed in M & DPRIME; values. It was observed that the peaks shifted to the high-frequency region with the increase in temperature. The activation energies were also calculated from the conductivity parameters and a decrease was observed in the activation energies as the frequency increased. Regardless of temperature and frequency, the higher dielectric loss of the fabricated diode compared to its dielectric constant can be advantageous for certain heating or electromagnetic absorption applications.