Temperature dependence of forward and reverse bias current–voltage characteristics in Al–TiW–PtSi/n-Si Schottky barrier diodes with the amorphous diffusion barrier

Abstract

The forward and reverse bias current–voltage (I–V) characteristics of Al–TiW–PtSi/n-Si SBDs which are fabricated by a magnetron sputtering method, were measured in the temperature and applied bias voltage ranges of 80–360K and (−25)–(5)V, respectively. The diode matrix contains 14 Al–TiW–PtSi/n-Si diodes with the rectifier contact areas between 1×10−6cm2 and 14×10−6cm2. It was found that the ideality factor n decreases, while the zero-bias Schottky barrier height (ΦB0) increases with increasing temperature. The conventional Richardson plot was also found to be nonlinear especially at low temperatures. Therefore, ΦB0 vs. q/kT plot was drawn to obtain an evidence of a Gaussian Distribution (GD) of barrier heights (BHs), and mean BH and zero-bias standard deviation values were obtained from this plot as Φ¯B=0.856eV and σ0=95mV, respectively. Thus, a modified ln(I0/T2)-q2σ02/2k2T2 vs. q/kT plot gives Φ¯B and the Richardson constant (A∗) as 0.820eV and 169Acm−2K−2, respectively. On the basis of obtained results, it can be concluded that the hexagonal emptiness in crystal lattice of Si(111) strongly influence the electric parameters of Al–TiW–PtSi/n-Si structures and its I–V characteristics can be successfully explained on the basis of a thermionic emission (TE) mechanism with Gaussian distribution (GD) of the barrier heights (BHs).The crossing of the experimental semi-logarithmic reverse bias lnI–V plots appears as an abnormality considering the conventional behavior of ideal SBDs. This behavior could be expected for semiconductors in the temperature region where there is no carrier freezing-out which is non-negligible at low temperatures.