Preparation and Characterization of Epitaxial Yttrium Silicide on (111) Silicon

Abstract

AbstractEpitaxial YSi2-x films have been fabricated. The smooth ∼430 Å thick silicide films on Si(111) substrates were characterized by a Rutherford backscattering minimum channeling yield, Xmin = 8%. The best previously reported result, Xmin = 26%, was achieved using a relatively exotic e-beam heating method. By contrast we formed YSi2-x using a straightforward furnace annealing technique. We used improved Si surface cleaning procedures, sputter-deposited Y films, and performed two-stage anneals in a vacuum of ∼ 10−8 torr. The results of our work establish YSi2-x as one of the best epitaxial silicides. We describe our preparation technique as well as the evidence for epitaxy. Electrical measurements (Schottky barrier, temperature dependent resistivity, Hall effect) are also presented. Low temperature resistivity of YSi2-x is found to obey simple T5 Bloch's law. Based on resistivity data, YSi2-x appears to have a Debye temperature of 310 K. According to Hall measurements, it is an electronic conductor with n = 2.7 × 1022 cm−3 and the mean free path of electrons is ∼ 87 Å at 4.2 K. We measure a Schottky barrier height of 0.36 eV between YSi2-x, and n-type Si.