Electrical characterization of Ar-ion-bombardment-induceddamage in Au/Si and PtSi/Si Schottky barriercontacts

Abstract

Au/Si and PtSi/Si Schottky contacts were prepared onn-Si(100) substrates which had been previously subjected to anAr ion bombardment with well defined energies ranging from100 eV to 1.5 keV. Samples were investigated bycurrent-voltage (I-V) measurements, ballisticelectron emission microscopy (BEEM) and deep-level transientspectroscopy (DLTS). Both I-V and BEEM results showthat the effective Schottky barrier height (SBH) decreases withincreasing Ar ion energy. The lowering of the barrier height isattributed to the bombardment-induced donor-like defects withrelatively high densities near the silicon surface. DLTSspectra show the presence of defect levels both in the formof discrete energy levels and as a continuum of states. Theoxygen-vacancy pair located at 0.16 eV below theconduction band is the dominant defect for the samples bombardedby 100 and 200 eV Ar ions and its peak signal intensity issimilar for the two energies. For 300 eV or higher-energy ion-bombarded samples, other defects develop and become dominant.Their peak signal intensities increase monotonically with Arion energy. The variation of the DLTS spectra is in qualitativeagreement with the tendency of effective SBH lowering forincreasing energy of the bombarding Ar ions.