Current-voltage characteristics and X-ray diffraction study of Pd/Si1-xGex Schottky contacts

The electrical characteristics of Pd/p-Si1-xGex Schottky contacts have been investigated. The Schottky contacts were formed by depositing Pd metal on substrates at room temperature (RT = 300K) and at low temperature (LT = 77K). Post annealing was performed in nitrogen atmosphere at 450 and 550 degrees C, respectively, to study the effect of silicide formation on contact characteristics. The current-voltage measurements showed that the barrier height, phi(B), decreased with the increase of the gemanium composition. The contact postannealed at 550 degrees C showed a current transport mechanism obviously different from the as-deposited Schottky contacts. Nearly identical characteristics were observed for the low temperature deposited contacts and the room temperature deposited contacts with 550 degrees C post-annealing. They both showed thermionic emission dominated transport mechanism. X-ray diffraction technique was used to characterize the effect of different temperature treatments on the crystal structure. The full width at half maximum of Si1-xGex(400) phase decreased at low temperature deposited sample, while it increased at room temperature deposition.