Structural evolution and bandgap modulation of layered β-GeSe2 single crystal under high pressure

• Published in: Chinese physics B Vol. 31; no. 7; pp. 482 - 489
• Main Authors: Xie, Hengli, Wang, Jiaxiang, Wang, Lingrui, Yan, Yong, Guo, Juan, Gao, Qilong, Chao, Mingju, Liang, Erjun, Ren, Xiao
• Format: Journal Article
• Language: English
• Published: Chinese Physical Society and IOP Publishing Ltd 01.06.2022; Key Laboratory of Materials Physics of Ministry of Education,School of Physics and Microelectronics,Zhengzhou University,Zhengzhou 450052,China%College of Physics and Materials Science,Henan Normal University,Xinxiang 453007,China
• Subjects: high pressure; layered material; Raman spectroscopy scattering; structural phase transition; structural phase transition; Raman spectroscopy scattering; layered material; high pressure
• ISSN: 1674-1056; 2058-3834
• DOI: 10.1088/1674-1056/ac6db8

Germanium diselenide(GeSe2)is a promising candidate for electronic devices because of its unique crystal structure and optoelectronic properties.However,the evolution of lattice and electronic structure of β-GeSe2 at high pressure is still uncertain.Here we prepared high-quality β-GeSe2 single crystals by chemical vapor transfer(CVT)technique and performed systematic experimental studies on the evolution of lattice structure and bandgap of β-GeSe2 under pressure.High-precision high-pressure ultra low frequency(ULF)Raman scattering and synchrotron angle-dispersive x-ray diffrac-tion(ADXRD)measurements support that no structural phase transition exists under high pressure up to 13.80 GPa,but the structure of β-GeSe2 turns into a disordered state near 6.91 GPa and gradually becomes amorphous forming an irre-versibly amorphous crystal at 13.80 GPa.Two Raman modes keep softening abnormally upon pressure.The bandgap ofβ-GeSe2 reduced linearly from 2.59 eV to 1.65 eV under pressure with a detectable narrowing of 36.5％,and the sample under pressure performs the piezochromism phenomenon.The bandgap after decompression is smaller than that in the at-mospheric pressure environment,which is caused by incomplete recrystallization.These results enrich the insight into the structural and optical properties of β-GeSe2 and demonstrate the potential of pressure in modulating the material properties of two-dimensional(2D)Ge-based binary material.