Influence of thin interfacial silicon oxide layers on the Schottky-barrier behavior of Ti on Si(100)

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Abstract
The Schottky-barrier height of Ti on both n-type and p-type Si(100) with thin surface oxide present has been measured in the temperature range 85–355 K with the use of a current-voltage technique. Auger-electron spectroscopy and x-ray photoemission spectroscopy were used to characterize the Si(100) surfaces prior to metal deposition, and to monitor the reaction between Ti and Si upon annealing. The results showed that only a few monolayers of silicon oxide on the initial Si(100) surfaces have a large effect on the barrier height and its temperature dependence, compared with that of silicide formation. The temperature dependence of the barrier height was found to deviate from the predictions of models of the Schottky-barrier formation based on the suggestion of Fermi-level pinning in the center of the semiconductor indirect band gap. However, annealing to sufficiently high temperatures to reduce the interfacial oxide by the Ti resulted in values of barrier heights on both n-type and p-type Si(100) similar to those on clean Si(100) and in temperature dependence of barrier heights consistent with the predictions of these models. A higher temperature was required to initiate the silicide formation reaction for Ti on Si(100) with few monolayers of surface oxide present. For the reacted silicide phase the temperature dependence of the n-type and p-type barrier heights was also found to be consistent with the predictions of these models of barrier formation.

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