ION-BEAM SYNTHESIS OF BURIED ALPHA-FESI2 AND BETA-FESI2 LAYERS

Using high dose implantation of Fe+ into (111)Si, followed by rapid thermal annealing (RTA) at 1150-degrees-C for 10 s, we fabricated continuous buried layers of the metallic alpha-FeSi2 phase. Rutherford backscattering experiments indicate that these layers contain a large number of Fe vacancies, up to 18%. By implanting through a SiO2 mask, we produced Schottky diodes with idealty factors of 1.4 +/- 0.1 and a Schottky barrier height of (PHI-B = 0.84 +/- 0.03 eV on (111) n-Si. In this letter we report for the first time the formation of the semiconducting stoichiometric FeSi2 (beta-FeSi2) phase by annealing the buried alpha-FeSi2 layers below the phase transition temperature of 937-degrees-C; specifically at 750-degrees-C for 20 h.