Electrical characteristics of Ti/Si(100) interfaces

Abstract

The Schottky-barrier height of Ti/Si(100) interfaces formed by sputter deposition of Ti on both n- and p-type Si(100) has been measured in the temperature range 77-355 K with the use of current- and capacitance-voltage techniques. Auger-electron and x-ray photoemission spectroscopies were used to characterize the Si(100) surfaces prior to metal deposition, and to monitor the reaction between Ti and Si upon heat treatment. The results showed that intermixing of Ti and Si has very little or no effect on the n- and p-type barrier heights. Silicide formation was found to result in only a small change in n- and p-type barrier heights of less than 0.1 eV. Furthermore, it was found that for only the metal-Si and silicide-Si interfaces with ideal thermionic-emission behavior the n- and p-type barrier heights decreased with increasing temperature and with coefficients approximately equal to one-half the temperature coefficient of the indirect energy gap in Si. These results are consistent with the predictions of models of Schottky-barrier formation which are based on the suggestion of Fermi-level pinning in the center of the semiconductor indirect energy gap. These results thus further confirm the dependence of both n- and p-type silicon barrier heights on temperature.