Phase formation sequences in the silicon-phosphorus system: Determined by in-situ synchrotron and conventional X-ray diffraction measurements and predicted by a theoretical model

Abstract

The phase formation sequences of Si-P alloy thin films with P concentrations between 20 and 44 at.% have been studied. The samples were annealed at progressively higher temperatures and the newly formed phases were identified both after each annealing step by ex-situ conventional X-ray diffraction (XRD) and continuously by in-situ synchrotron XRD. It was found that Si was the only phase to form in a sample with 20at.%P since the evaporation of P at the crystallization temperature prevented phosphides from forming. For a sample with 30at.%P, the Si12P5 phase formed prior to the SiP phase. For samples with 35 and 44at.%P, the formation of SiP preceded the formation of the Si12.P5 phase. The experimentally determined phase formation sequences were successfully predicted by a proposed model. According to the model, the first and second crystalline phases to form are those with the lowest and next-lowest crystallization temperatures of the competing compounds predicted by the Gibbs free-energy diagram. © 1997 Taylor & Francis Group, LLC.