CC BY
19LM-O-22
Laser-Induced Crystallization Kinetics of GeTe and Ge2Sb2Te5
Thin Films
A.A. Burtsev, V.V. Ionin, A.V. Kiselev, N.N. Eliseev, V.A. Mikhalevsky, and A.A. Lotin
ILIT RAS — Branch ofFSRC "Crystallography and Photonics" RAS, 140700, Shatura, Svyatoozerskaya Str., 1,
Moscow Region, Russia
Main author email address: tonyiplit@gmail.com
Thin film chalcogenide materials based on germanium telluride (GeTe, Ge2Sb2Te5) are widely used in photonic and optoelectronic devices [1]. These alloys have very high amorphization and crystallization rates in the order of nanoseconds which, combined with large cyclability and a pronounced property contrast between the crystalline and amorphous phases [2]. In this study researching of the crystallization process of chalcogenide (GeTe and Ge2Sb2Te5) thin films (100 nm), deposited by vacuum thermal sputtering, is presented. The researching includes in situ optical parameters measurement and X-ray diffractometry (XRD). Phase transitions in films were induced by nanosecond pulsed laser radiation with «top hat» intensity distribution [3,4]. The threshold fluences to induce crystallization are determined for both materials. Structural information was characterized by XRD. The progress of the phase transition can be monitored using the increase in reflectance upon crystallization and analyzed using the Johnson-Mehl-Avrami-Kolmogorov model [5]. Results demonstrate different transition mechanism: one-step crystallization for GeTe [6] and two-step crystallization for Ge2Sb2Te5 [7].
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