Polar surface of ferroelectric nanodomains in GeTe thin films

Croes, Boris; Cheynis, Fabien; Müller, Pierre; Curiotto, S.; Leroy, F.

doi:10.1103/physrevmaterials.6.064407

Cited by 5 publications

(1 citation statement)

References 46 publications

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“…Kanjanachuchai et al studied morphological changes in Ⅲ−Ⅴ heteroepitaxial thin films and used LEEM to observe the nucleation and kinetics of Ⅲ droplets [62] . Mandziak et al optimized the growth parameters and Fe doping for NiO thin films deposited on Ru(0001) using LEED [63] . Croes et al used LEEM to explore the volume fraction of ferroelectric domains and domain sizes across a wide range of film thicknesses, demonstrating that interfacial misfit dislocations formed during growth play a vital role in the stability of ferroelectric nanodomains [64] .…”

Section: Low-energy Electron Microscopy (Leem)mentioning

confidence: 99%

Development of in situ characterization techniques in molecular beam epitaxy

Shen,

Zhan,

et al. 2024

J. Semicond.

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Ex situ characterization techniques in molecular beam epitaxy (MBE) have inherent limitations, such as being prone to sample contamination and unstable surfaces during sample transfer from the MBE chamber. In recent years, the need for improved accuracy and reliability in measurement has driven the increasing adoption of in situ characterization techniques. These techniques, such as reflection high-energy electron diffraction, scanning tunneling microscopy, and X-ray photoelectron spectroscopy, allow direct observation of film growth processes in real time without exposing the sample to air, hence offering insights into the growth mechanisms of epitaxial films with controlled properties. By combining multiple in situ characterization techniques with MBE, researchers can better understand film growth processes, realizing novel materials with customized properties and extensive applications. This review aims to overview the benefits and achievements of in situ characterization techniques in MBE and their applications for material science research. In addition, through further analysis of these techniques regarding their challenges and potential solutions, particularly highlighting the assistance of machine learning to correlate in situ characterization with other material information, we hope to provide a guideline for future efforts in the development of novel monitoring and control schemes for MBE growth processes with improved material properties.

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Section: Low-energy Electron Microscopy (Leem)mentioning

confidence: 99%

Development of in situ characterization techniques in molecular beam epitaxy

Shen,

Zhan,

et al. 2024

J. Semicond.

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Trends in GeTe Thermoelectrics: From Fundamentals to Applications

Li,

Shi,

Chen

2024

Adv Funct Materials

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Germanium telluride (GeTe) with ultrafast ferroelectric transition, Rashba‐like electronic transport, and anomalous phonon anharmonicity are historically studied for potential memorizing and thermoelectric applications. Due to recent breakthroughs in spintronics, valleytronics, orbitronics, pre‐eminent GeTe thermoelectrics have re‐attracted enormous interest from both academia and industries, with increasing reports of significant figure‐of‐merit over 2.7 and the maximum efficiency of up to 17.0%. Here, the emerging trends in advancing GeTe thermoelectrics, starting from fundamentals of phase transformation, crystal structure, bonding mechanisms, and transport characteristics, with a highlight on the roles of Ge_4s2 lone pairs, are timely overviewed. Technical insights in synthesis, characterization, property measurement, and computation are then summarized. After that, several innovative strategies for increasing the figure‐of‐merit, including entropy engineering, nanostructuring, and hybridization, which will further benefit near‐room‐temperature and n‐type performance, are examined. Moreover, high‐density and high‐efficiency devices with broad working temperatures are discussed as a result of rational configurational and interfacial design. In the end, perspective remarks on the challenges and outlook envisaging for next‐generation GeTe thermoelectrics, which will play a prominent role in future energy and environmental landscapes, are provided.

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Thermomechanic behavior of epitaxial GeTe ferroelectric films

Croes,

Cheynis,

Texier

et al. 2023

Journal of Applied Physics

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A key development toward new electronic devices integrating memory and processing capabilities could be based on the electric control of the spin texture of charge carriers in semiconductors. In that respect, GeTe has been recently recognized as a promising ferroelectric Rashba semiconductor, with giant spin splitting of the band structure, due to the inversion symmetry breaking arising from ferroelectric polarization. Here, we address the temperature dependence of the ferroelectric structure of GeTe thin films grown on Si(111). We demonstrate the hysteretic behavior of the ferroelectric domain density upon heating/cooling cycles by low energy electron microscopy. This behavior is associated with an abnormal evolution of the GeTe lattice parameter as shown by x-ray diffraction. We explain these thermomechanical phenomena by a large difference of thermal expansion coefficients between the film and the substrate and to the pinning of the GeTe/Si interface. The accumulated elastic energy by the GeTe thin film during sample cooling is released by the formation of a-nanodomains with in-plane ferroelectric polarization components.

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Polar surface of ferroelectric nanodomains in GeTe thin films

Cited by 5 publications

References 46 publications

Development of in situ characterization techniques in molecular beam epitaxy

Development of in situ characterization techniques in molecular beam epitaxy

Trends in GeTe Thermoelectrics: From Fundamentals to Applications

Thermomechanic behavior of epitaxial GeTe ferroelectric films

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