Hexagonal Silicon Formation and Its Phase Transformability
At a Glance
Section titled âAt a Glanceâ| Metadata | Details |
|---|---|
| Publication Date | 2025-05-27 |
| Journal | Advanced Functional Materials |
| Authors | M. S. Nisha, Yadu Chandran, Abhay A. Sagade, Viswanath Balakrishnan, Oleksandr O. Kurakevych |
| Institutions | Centre National de la Recherche Scientifique, Technische Universität Dresden |
| Citations | 3 |
Abstract
Section titled âAbstractâAbstract The pivotal role of silicon (Si) in semiconductor technology is wellâestablished; however, its hexagonal diamond (hd) crystal structure remains underexplored. This study addresses the paucity of microscopic evidence concerning the formation and phase transformation behavior of hdâSi up to 1000 °C. Utilizing instrumented nanoindentation and subsequent annealing, the hdâSi phase is obtained from a rhombohedral (R8) and bodyâcentered cubic (BC8) mixture within a diamond cubic silicon (dcâSi) wafer. In situ characterization reveals that hdâSi undergoes a reversible phase transition to a metallic βâtin (Sn) phase under indentation loading, reverting to an R8/BC8 mixture upon unloading, thereby providing experimental confirmation of prior theoretical predictions. Thermal stability assessments indicate that hdâSi remains stable beyond â700 °C and transitions to dominantly dcâSi at 1000 °C, with traces of hdâSi persisting. Notably, annealing at 500 and 700 °C yields largeâarea textured hdâSi nanocrystals with slight misorientations featuring 2H, 4H, and 6H polytypes. Interestingly, the dcâSi formed from hdâSi upon annealing at 1000 °C also transforms to a metallic βâSn phase during Berkovich indentation and reverts to an R8/BC8 mixture upon unloading. This work provides critical insights into the highâpressure phases of Si, paving the way for future studies on phase engineering and stabilization for advanced semiconductor applications and material innovations.