The Richardson constant and barrier inhomogeneity at Au/Si3N4/n-Si (MIS) Schottky diodes

Abstract

Si3N4 films were deposited on n-type silicon substrate by the radio frequency magnetron sputtering technique. The current–voltage (I–V) characteristics of Au/Si3N4/n-Si (metal–insulator–semiconductor) Schottky diodes were investigated in the temperature range of 160–400 K. Experimental results show an abnormal increase in the zero-bias barrier height (BH) (ΦBo) and a decrease in the ideality factor (n) with increasing temperature. This behavior is attributed to barrier inhomogeneities by assuming a Gaussian distribution (GD) of BHs. The conventional Richardson plot (ln(Io/T2) versus 1000/T) exhibits a linearity above about 300 K. The values of activation energy (Ea) and Richardson constant (A*) were found to be 0.350 eV and 1.242 × 10–3 A cm−2 K−2 from the slope and the intercept at the ordinate of the linear region of this plot, respectively. Also, we attempted to draw a ΦBo versus q/2kT plot to determine evidence of the GD of BHs, and the values of and σs = 0.137 eV for the mean BH and zero-bias standard deviation, respectively, were obtained from this plot; then, a modified ln(Io/T2) − q2σs2/2k2T2 versus q/kT plot gives and A* as 0.992 eV and 108.228 A cm−2 K−2, respectively. This value of A* is very close to the theoretical value of 112 A cm−2 K−2 for n-type Si.