The investigation of temperature dependence current-conduction mechanism and electrical characteristics of Au/Si3N4/4H n-SiC (MIS) stuctures

The current-voltage (I-V), capacitance-voltage (C-V) and conductance-voltage (G/w-V) characteristics of Au/Si3N4/4H n-SiC metal-insulator-semiconductor (MIS) structure/ Schottky diodes were measured in the temperature range of 160-400 K. The calculated zero bias barrier height (ΦBo) and the ideality factor (n) values according to thermionic emission (TE) theory show strong temperature dependence. While ΦBo increases, n decreases with increasing temperature. Such behaviour is attributed to inhomogeneties of Schottky barrier by assuming a Gaussian distribution (GD) of barrier heights (BHs) at 4H n-SiC/Si3N4 interface. We attempted to draw a ΦBo vs q/2kT plot to obtain evidence of a Gaussian distribution of the BHs and the values of ΦBo = 1.4 eV and σo= 0.169 V for the mean BH and standard deviation at zero bias, respectively, have been obtained from this plot. Thus, the modified [ln(Io/T2)-q2σo2/2k2T2] vs q/kT plot gives ΦBo and A* as 1.53 eV and 137.21 Acm-2K-2, respectively. This value is very close to the theoretical value of 146 A K-2 cm-2 for n-type SiC. Hence, it has been concluded that the temperature dependence of the forward I-V characteristics of the Au/Si3N4/4H n-SiC structure can be successfully explained on the basis of TE mechanism with a GD of the BHs. The forward and reverse bias C-V and G/w-V characteristics of Au/Si3N4/4H n-SiC MIS Schottky diodes have been investigated a wide temperature and the frequency range of 160-400 K and 10-1000 kHz, respectively.