2025/08/25 by Kim, Joonho, Lee, Kihyun, Jung, Joong-Eon +3
#Applied Physics (physics.app-ph) #FOS: Physical sciences #Materials Science (cond-mat.mtrl-sci)
paper · doi:10.48550/arxiv.2508.17997
Understanding phase transitions between crystalline phases of a material is crucial for both fundamental research and potential applications such as phase-change memory. In this study, we investigate the phase transition between GeSe crystalline polymorphs induced by either global annealing at moderate temperatures or localized laser-induced heating. The highly conductive gamma-GeSe transforms into semiconducting, single-crystalline alpha-GeSe while preserving a well-aligned crystal orientation. The distinct structural and electronic properties at the gamma-GeSe/alpha-GeSe interface were investigated by transmission electron microscopy analysis. We propose that the clustering of Ge vacancies in the gamma-GeSe phase at elevated temperatures is a key mechanism driving the transition, leading to the formation of alpha-GeSe through the segregation of a minor GeSe2 phase. Furthermore, we observe a high electrical resistance contrast of approximately 107 between gamma-GeSe and alpha-GeSe, underscoring the potential of GeSe as a model polymorphic system for electronic applications, including phase-change memory.