Comparable Study on Proton Radiation Effects for Amorphous and Crystalline Ge₂Sb₂Te₅

Displacement damage to the structure and properties of phase-change materials caused by high-energy particle radiation is a major challenge to the development of optical storage systems for space applications. In this article, a 10 MeV proton irradiation was carried out on an amorphous and crystalline phase-change material of Ge2Sb2Te5 (namely, a-GeSbTe and c-GeSbTe), respectively, and radiation-induced local structural and optical property changes were then studied using Raman spectroscopy and X-ray photoelectron spectroscopy (XPS) as well as a spectrophotometer. The results indicated that proton bombardment caused the partial breaking of the Sb-Te and Ge-Te bonds in both the a-GeSbTe and c-GeSbTe samples, but with a greater number of broken bonds in c-GeSbTe which led to an obvious drop in optical reflectivity together with an enhanced surface roughness as compared to a-GeSbTe. Stopping and range of ions in matter (SRIM) simulations further verified that c-GeSbTe experienced a higher degree of displacement damage, with peak damage values up to
$3.3\times 10^{-5}$
dpa. Meanwhile, vacancies in a-GeSbTe tended to gather toward the film bottom, while those in c-GeSbTe were commonly clustered near the film middle. This article provides crucial insights into understanding the response of Ge2Sb2Te5 to proton irradiation.