Gaussian distribution of inhomogeneous barrier height in Ag/p-Si (1 0 0) Schottky barrier diodes

Abstract

The current–voltage ( I– V) measurements on Ag/p-Si Schottky barrier diodes in the temperature range 125–300 K were carried out. The I– V analysis based on the thermionic emission (TE) theory has revealed an abnormal decrease of apparent barrier height and increase of ideality factor at low temperature. It is demonstrated that these anomalies result due to the barrier height inhomogeneities prevailing at the metal–semiconductor interface. A Φ b0 versus q/2 kT plot was drawn to obtain evidence of a Gaussian distribution of the barrier heights, and values of Φ ̄ b0 =0.780 eV and σ s0=0.0906 V for the mean barrier height and standard deviation at zero bias have been obtained from this plot, respectively. Furthermore, the mean barrier height and the Richardson constant values were obtained as 0.773 eV and 15.53 A K −2 cm −2, respectively, by means of the modified Richardson plot, ln( I 0/ T 2)−( q 2 σ s0 2/2 k 2 T 2) versus 1000/ T. Thus, it has been concluded that the temperature dependence of the I– V characteristics of the Schottky barrier on p-type Si can be successfully explained on the basis of thermionic emission mechanism with Gaussian distribution of the barrier heights. Moreover, the value of the Richardson constant was found to be 15.53 A K −2 cm −2, which is close to the theoretical value of 32 A K −2 cm −2 used for the determination of the zero-bias barrier height.