2021/01/01 by Martin Hafermann, Hafermann, Martin, Robin Schock +9
Engineering · Materials Science · #Applied Physics (physics.app-ph) #Chalcogenide Semiconductor Thin Films #Disordered Systems and Neural Networks (cond-mat.dis-nn) #FOS: Physical sciences #Glass properties and applications #Materials Science (cond-mat.mtrl-sci) #Mesoscale and Nanoscale Physics (cond-mat.mes-hall) #Nonlinear Optical Materials Studies #Optics (physics.optics) #Phase-change materials and chalcogenides
paper · pdf · doi:10.48550/arxiv.2109.00716
openalex publication_date 2021/09/02 · openalex created_date 2022/07/25 · openalex updated_date 2026/07/28
Phase-change materials serve a broad field of applications ranging from\nnon-volatile electronic memory to optical data storage by providing reversible,\nrepeatable, and rapid switching between amorphous and crystalline states\naccompanied by large changes in the electrical and optical properties. Here, we\ndemonstrate how ion irradiation can be used to tailor disorder in initially\ncrystalline Ge2Sb2Te5 (GST) thin films via the intentional creation of lattice\ndefects. We found that continuous Ar ion irradiation at room temperature of GST\nfilms causes complete amorphization of GST when exceeding 0.6 (for rock-salt\nGST) and 3 (for hexagonal GST) displacements per atom (ndpa). While the\ntransition from rock-salt to amorphous GST is caused by progressive\namorphization via the accumulation of lattice defects, several transitions\noccur in hexagonal GST upon ion irradiation. In hexagonal GST, the creation of\npoint defects and small defect clusters leads to disordering of intrinsic\nvacancy layers (van der Waals gaps) that drives the electronic metal-insulator\ntransition. Increasing disorder then induces a structural transition from\nhexagonal to rock-salt and then leads to amorphization. Furthermore, we\nobserved different annealing behavior of defects for rock-salt and hexagonal\nGST. The higher amorphization threshold in hexagonal GST compared to rock-salt\nGST is caused by an increased defect-annealing rate, i.e., a higher resistance\nagainst ion-beam-induced disorder. Moreover, we observed that the recovery of\ndefects in GST is on the time scale of seconds or less at room temperature.\n