Phase Formation in the Pt/Inp Thin Film System

Abstract

InP substrates with 40nm metal films of Pt were encapsulated in SiO2, and isochronally annealed up to 600°C in flowing forming gas. The composition and morphology of the phases that formed were studied using x-ray diffraction, Rutherford Backscattering, and transmission electron microscopy.Results show that the Pt/InP system begins interacting at 300°C. TEM analysis of the 350°C anneal shows unreacted Pt and and additional polycrystalline phases, with no observed orientation relationship with the substrate. The Pt layer has been completely consumed by 400°C, with a uniform reacted layer indicated by RBS. At high temperatures (between 500°C and 600°C), the reaction products are PtIn2 and PtP2. The two phases show a tendency for phase separation, with a higher concentration of PtP2 at the InP/reacted layer interface. The phosphide phase also shows a preferred orientation relationship with the substrate.