Probing the electric and thermoelectric response of ferroelectric 2H and 3R α-In2Se3

• Published in: Applied physics letters 2024-06, Vol.124 (25)
• Main Authors: Rahimi, M., Sobnath, K., Chen, L., Mallet, F., Lafarge, P., Barraud, C., Alekhin, A., Brochard-Richard, C., Bouaziz, M., Chaste, J., Ouerghi, A., Della Rocca, M. L.
• Format: Article
• Language: English
• Subjects: Charge transport; Devices; Electric potential; Engineering Sciences; Ferroelectric materials; Ferroelectricity; Micro and nanotechnologies; Microelectronics; Polarization; Thermoelectricity; Thin films; Voltage
• ISSN: 0003-6951; 1077-3118
• DOI: 10.1063/5.0202871

Two-dimensional van der Waals ferroelectric materials play an important role in a wide spectrum of semiconductor technologies and device applications. Integration of ferroelectrics into 2D-layered material-based devices is expected to offer intriguing working principles and add desired functionalities for next-generation electronics. Here, we investigate the electric and thermoelectric properties of thin layers of the 2H and 3R polymorphs of α-In2Se3 embedded in solid-state three-terminal devices. Charge transport measurements reveal a hysteretic behavior that can be ascribed to the effect of ferroelectric polarization at the metal electrode/2D semiconductor interfaces. The thermoelectric investigation of the same devices unveils a well-defined negative signal of the order of 100–200  μV/K in absolute value for the 2H polymorph, showing a slight modulation as a function of the gate voltage. An analogous but noisy thermoelectric voltage is measured for devices based on the 3R polymorph, where indeed a constant finite transversal offset in the 100  μV-few mV range is detected, which does not depend on the applied temperature gradient. We argue that these experimental observations are related to a strong residual in-plane ferroelectric polarization in the 3R α-In2Se3 polymorph thin layer. Our results show that the thermoelectric response is a fine probe of the ferroelectric character of 2D layered α-In2Se3.