Structural transformation and phase change properties of Se substituted GeTe
Roopali Shekhawat1, Haritha Pamuluri1, Vinod Erkkara Madhavan2
1Department of Physics, Indian Institute of Science, Bengaluru, 560012, India.
Scientific Reports
|April 8, 2021
Summary
Selenium substitution in germanium telluride (GeTe) alloys enhances phase change properties. Increasing selenium (Se) content alters crystal structure and significantly boosts resistivity contrast, reducing power for phase change memory devices.
Area of Science:
- Materials Science
- Solid State Physics
- Nanotechnology
Background:
- Germanium telluride (GeTe) is a key material for phase change memory (PCM) devices.
- Tuning the properties of GeTe through compositional changes is crucial for optimizing PCM performance.
Purpose of the Study:
- To investigate the impact of selenium (Se) substitution for tellurium (Te) on the structural and phase change properties of GeTe.
- To explore the potential of GeTe$_{1-x}$Se$_{x}$ alloys for advanced phase change memory applications.
Main Methods:
- Preparation of GeTe$_{1-x}$Se$_{x}$ alloys in bulk and thin film forms (0 ≤ x ≤ 1.0).
- Structural analysis using Rietveld Refinement to confirm phase transformations.
- Characterization of electrical resistivity, transition temperature, and threshold current in thin films.
Main Results:
- A structural transformation from rhombohedral to orthorhombic was observed with increasing Se content.
- Rietveld Refinement indicated a decrease in both short and long bond lengths with Se substitution.
- The amorphous-to-crystalline transition temperature increased with Se substitution.
- Electrical resistivity contrast between amorphous and crystalline states increased significantly, reaching 10$^6$ for GeTe$_{0.5}$Se$_{0.5}$.
- Threshold current for device switching decreased with Se substitution.
Conclusions:
- Selenium substitution effectively controls and tunes the crystalline structure, resistance, bandgap, transition temperature, and threshold voltage of GeTe.
- The observed property enhancements are conducive to improved performance in phase change memory applications.
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