Abstract
Thecomplexphasediagramofgermaniumallowsforexotic crystalline phases recoverable from high pressure. Among these, the tetragonal st12 phase is unusual as it shares characteristics with amorphous Ge resulting in desirable band-gap characteristics. Here, we leverage a high neutron flux and large volume pressure capabilities to characterize st12-Ge and its dynamics upon conversion to diamond-cubic Ge with inelastic neutron scattering. Weexploit the characteristics of time-of-flight neutron scattering for time-resolved investigations. This analysis may suggest the existence of a transient disordered state upon annealing befitting the known structural relationship between st12-Ge and amorphous Ge, a relationship that can open the potential for band-gap tuning.
| Original language | English |
|---|---|
| Article number | 014113 |
| Journal | Physical Review B |
| Volume | 112 |
| Issue number | 1 |
| DOIs | |
| State | Published - Jul 24 2025 |
Funding
We gratefully acknowledge discussions with Camille Bernal-Choban (University of Illinois, Urbana-Champaign) and Brent Fultz (California Institute of Technology) on the dispersion curves of the diamond structure. We also gratefully acknowledge Jamie J. Molaison (ORNL) for assistance during the setup for high-pressure synthesis. Discussions with Jiao Lin and Jennifer Niedziela on the use of the multiphonon software for processing the neutron data were helpful. We are also grateful for Y. Q. Chen sharing the diamond cubic Ge DFT results that are included with INSPIRED. M.-E.D. also acknowledges support from the Canadian Light Source, Inc. Inelastic neutron scattering was performed at the ARCS beamline, and sample synthesis was performed at the Spallation Neutrons and Pressure (SNAP) beamline. This research used resources at the Spallation Neutron Source, a DOE Office of Science User Facility operated by the Oak Ridge National Laboratory under Proposals No. 24888, No. 25388, and No. 32963. This manuscript has been authored by UT-Battelle, LLC under Contract No. DE-AC05-00OR22725 with the U.S. Department of Energy.