Preparation and characterization of epitaxial yttrium silicide on (111) silicon

Epitaxial YSi/sub 2-x/ films have been fabricated. The smooth -- 430 A thick silicide films on Si(111) substrates were characterized by a Rutherford backscattering minimum channeling yield, chi/sub min/ = 8%. The best previously reported result, chi/sub min/ = 26%, was achieved using a relatively exotic e-beam heating method. By contrast the authors formed YSi/sub 2-x/ using a straightforward furnace annealing technique. The authors used improved Si surface cleaning procedures, sputter-deposited Y films, and performed two-stage anneals in a vacuum of -- 10/sup -8/ torr. The results of their work establish YSi/sub 2-x/ as one of the best epitaxial silicides. The authors describe their preparation technique as well as the evidence for epitaxy. Electrical measurements are also presented. Low temperature resistivity of YSi/sub 2-x/ is found to obey simple T/sup 5/ Bloch's law. Based on resistivity data, YSi/sub 2-x/ appears to have a Debye temperature of 310 K. According to Hall measurements, it is an electronic conductor with n = 2.7 x 10/sup 22/ cm/sup -3/ and the mean free path of electrons is -- 87 A at 4.2 K. The authors measure a Schottky barrier height of 0.36 eV between YSi/sub 2-x/ and n-type Si