Stress limited scaling in Ge₂Sb₂Te₅

The influence of stress on the phase change behaviour of Ge ₂Sb₂Te₅ encapsulated by ZnSSiO₂ and TiN is investigated using temperature dependent Extended X-ray Asbsorption Fines Structure and Ellipsometry to determine the crystallisation temperature. The encapsulation material surrounding the Ge₂Sb₂Te ₅ has an increasingly dominant effect on the material's ability to change phase and can cause a profound increase in its crystallization temperature. We have experimentally shown that the increased crystallization temperature originates from compressive stress exerted from the encapsulation material. By minimizing the stress we have maintained the bulk crystallization temperature in Ge₂Sb₂Te₅ films just 2 nm thick.