研究目的
Investigating the phase relation between supercooled liquid silicon (l-Si) and amorphous silicon (a-Si) to confirm the idea of a first-order phase transition between these two metastable phases.
研究成果
The study confirmed the first-order phase transition between supercooled l-Si and a-Si, supporting Turnbull's proposal. It demonstrated that a-Si can be formed from supercooled l-Si below the melting temperature of a-Si and observed the melting of a-Si due to latent heat release.
研究不足
The study was limited by the difficulty in accessing temperatures far below the melting point for observing the liquid-liquid phase transition (LLPT) and the challenge in completely preventing recalescence during quenching.
1：Experimental Design and Method Selection:
The study used electrostatic levitation to supercool l-Si samples and a piston anvil device for rapid quenching. The phase relation was investigated by observing the temperature-time profile and the structural changes during solidification and melting.
2：Sample Selection and Data Sources:
High-purity polycrystalline Si samples were used, levitated and heated in a vacuum chamber.
3：List of Experimental Equipment and Materials:
Electrostatic levitator, semiconductor lasers, pyrometer, high-speed camera, SEM, TEM, EBSD, EELS.
4：Experimental Procedures and Operational Workflow:
Samples were levitated, heated, supercooled, and quenched. The temperature was monitored, and the structural changes were analyzed post-quenching.
5：Data Analysis Methods:
Structural analysis was performed using SEM, TEM, EBSD, and EELS to identify the phases and their transitions.
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high-speed camera
SA-X2
Photron
Used to capture the solidification and melting processes of the Si samples.
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electrostatic levitator
Used to levitate and supercool l-Si samples without a container.
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semiconductor lasers
Used to heat the levitated Si samples.
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pyrometer
IR-CAS
CHINO
Used to measure the temperature of the levitated samples.
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SEM
Used to analyze the microstructure of the quenched Si samples.
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TEM
Used for atomic characterization of the quenched Si samples.
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EBSD
Used to determine crystal orientations and identify amorphous regions in the samples.
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EELS
Used to analyze the electronic structure and composition of the samples.
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