Temperature and frequency effects on electrical and dielectric properties of n-4H SiC based metal–insulator-semiconductor (MIS) diode interlayered with Si₃N₄ thin film

Effects of frequency and temperature variations on the electrical properties of Au/Si₃N₄/n-4H SiC diode were investigated. The diode responses to the change in frequency with applied AC signal of varying frequencies and to the change in temperature controlled by cryogenic control system were discussed with considering possible deviation from ideality and effects of interface states at the junction. Depending on its capacitive and conductive characteristics, internal parasitic resistances were associated with the observed dielectric behaviors of the diode. With the use of Si₃N₄ layer, the values of complex dielectric constant were extracted and this parameter was found to be in a strong dependence of interface changes in low frequency region whereas this variation was very low at higher frequencies. In addition, there is a slight decrease in the dielectric constant with increasing temperature whereas the values of dielectric loss give a remarkable response to the temperature at forward bias region. Depending on these profiles, AC conductivity values were found in decreasing behavior with both frequency and temperature. From the temperature dependent behaviors, activation energies were calculated from the corresponding Arrhenius plots. Together with the series resistance of the diode and density of interface states, interface polarization was found in a dominant role in both complex dielectric and electric modulus characteristics of the diode.