ION-BEAM SYNTHESIS OF BURIED EPITAXIAL FESI2

We fabricated continuous buried layers of the metallic alpha-FeSi2 phase by high dose implantation of Fe+ into (111) silicon wafers and subsequent rapid thermal annealing at 1150-degrees-C for 10 s. As determined from Rutherford backscattering spectrometry, these alpha-FeSi2 layers have a stoichiometry of Fe0.83Si2, corresponding to approximately 17% iron vacancies. Schottky diodes were fabricated on n-type silicon with ideality factors of n = 1.4 +/- 0.1 and Schottky barrier heights of PHI(B) = 0.84 +/- 0.03 eV. Deep level transient spectroscopy measurements of these diodes showed a low concentration of iron in silicon of about 1 x 10(13) cm-3. Semiconducting stoichiometric beta-FeSi2 layers were produced by transforming buried alpha-FeSi2 layers into beta-FeSi2 by furnace annealing at 800-degrees-C for 17 h.