Abstract
Hydrostatically pressurized studies using diamond anvil cells on the structural phase transition of the free-standing screw-dislocation-driven (SDD) GaSe thin film synthesized by molecular beam epitaxy have been demonstrated via in-situ angle-dispersive synchrotron X-ray diffraction and Raman spectroscopy. The early pressure-driven hexagonal-to-rock salt transition at approximately ~ 20 GPa as well as the outstandingly structural-phase memory after depressurization in the SDD-GaSe film was recognized, attributed to the screw dislocation-assisted mechanism. Note that, the reversible pressure-induced structural transition was not evidenced from the GaSe bulk, which has a layer-by-layer stacking structure. In addition, a remarkable 1.7 times higher in bulk modulus of the SDD-GaSe film in comparison to bulk counterpart was observed, which was mainly contributed by its four times higher in the incompressibility along c-axis. This is well-correlated to the slower shifting slopes of out-of-plane phonon-vibration modes in the SDD-GaSe film, especially at low-pressure range (< 5 GPa). As a final point, we recommend that the intense density of screw dislocation cores in the SDD-GaSe lattice structure plays a crucial role in these novel phenomena.
Highlights
Pressurized studies using diamond anvil cells on the structural phase transition of the free-standing screw-dislocation-driven (SDD) GaSe thin film synthesized by molecular beam epitaxy have been demonstrated via in-situ angle-dispersive synchrotron X-ray diffraction and Raman spectroscopy
High purity of 200 nm-thick single-crystalline 2D ε-GaSe thin films have been epitaxial deposited on GaAs (001) substrate by molecular beam epitaxy (MBE) for the high-pressure experiments
Pressure-induced structural phase transition of the free-standing SDD-GaSe layer grown by MBE has been comprehensively investigated for the first time by in-situ angle-dispersion synchrotron X-ray diffraction (ADXRD) and Raman spectroscopy
Summary
Pressurized studies using diamond anvil cells on the structural phase transition of the free-standing screw-dislocation-driven (SDD) GaSe thin film synthesized by molecular beam epitaxy have been demonstrated via in-situ angle-dispersive synchrotron X-ray diffraction and Raman spectroscopy. Was confirmed, its band gap exhibited a strong redshift as compared to that of the bulk counterpart (~ 0.3 eV), which was mostly attributed to the lattice misalignment-induced strain near the screw-dislocation-core (SDC) regions and the substrate–layer interface-correlation[22,23] These raise an important question on how the structural and optical properties of a free-standing SDD-GaSe layer grown by MBE, i.e., only the effect of SDCs takes into account, respond to the gradual pressurization. The impact of SDCs in these phenomena is noticeable and discussed
Sign-in/Register to view highlights & summary Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
