Pulsed laser deposited GeTe-rich GeTe-Sb2Te3 thin films

Abstract

Pulsed laser deposition technique was used for the fabrication of Ge-Te rich GeTe-Sb2Te3 (Ge6Sb2Te9, Ge8Sb2Te11, Ge10Sb2Te13, and Ge12Sb2Te15) amorphous thin films. To evaluate the influence of GeTe content in the deposited films on physico-chemical properties of the GST materials, scanning electron microscopy with energy-dispersive X-ray analysis, X-ray diffraction and reflectometry, atomic force microscopy, Raman scattering spectroscopy, optical reflectivity, and sheet resistance temperature dependences as well as variable angle spectroscopic ellipsometry measurements were used to characterize as-deposited (amorphous) and annealed (crystalline) layers. Upon crystallization, optical functions and electrical resistance of the films change drastically, leading to large optical and electrical contrast between amorphous and crystalline phases. Large changes of optical/electrical properties are accompanied by the variations of thickness, density, and roughness of the films due to crystallization. Reflectivity contrast as high as ~0.21 at 405 nm was calculated for Ge8Sb2Te11, Ge10Sb2Te13, and Ge12Sb2Te15 layers.

Ge-Sb-Te Chalcogenide Thin Films Deposited by Nanosecond, Picosecond, and Femtosecond Laser Ablation

“…A higher Ge concentration was also reported in References [6,31,32] for Ge-Sb-Te thin films deposited by PLD using a KrF excimer laser (248 nm, 30 ns, 20 Hz) at a fluence of 2.6 J/cm 2 . However, the recorded deviations were lower than the ones reported in this paper.…”

“…Their work revealed that the deposited samples present a Te segregation on grain boundaries and surfaces. The composition of the main elements on the thin film surface was determined in Reference [32] by proton-induced X-ray emission (PIXE) and Rutherford back-scattering (RBS).…”

Crystallization Study of Ge‐Rich (GeTe)m(Sb2Te3)n Using Two‐Step Annealing Process

“…All the Raman spectra present the characteristic Bose peak (30–100 cm −1 ), although the shape of the peak is composition dependent. The spectra of a‐Ge 10 Sb 2 Te 13 (10:1) and a‐Ge 5 Sb 2 Te 8 (5:1) are similar to that of a‐GeTe (1:0) . In addition, they show: (i) a broad peak at ≈155 cm −1 , an initial expression of the Sb 2 Te 3 fraction whose intensity increases with n ; (ii) a mode at ≈103 cm −1 (black arrows in Figure ) which has not been reported so far.…”

“…However, GeSbTe (GST) with Ge‐rich composition remains the most promising material . One of the major challenges in the usage of Ge‐rich GST alloys is controlling the Ge or GeTe segregation upon crystallization . Thus, in order to obtain homogeneous phases for electronic devices, it is of great interest to find an industrial suitable way to govern this segregation effect.…”

Atomic layer deposition and tellurization of Ge–Sb film for phase-change memory applications

“…Besides, the conventional sputtering processes using GST targets result in Te-decient GST lms because of the higher volatility of Te element than those of others. 13,14 Atomic layer deposition (ALD) of the phase change material is the ideal solution and has been studied for the last decade. 15,16 Since the introduction of tellurium silyl compounds, ALD studies using chloride precursors and Te silyl precursors have been accelerated.…”