TY - JOUR
T1 - Pressure-induced amorphization and an amorphous-amorphous transition in densified porous silicon
AU - Deb, Sudip K.
AU - Wilding, Martin C.
AU - Somayazulu, Maddury
AU - McMillan, Paul F.
N1 - Deb, S. K., Wilding, M. C., Somayazulu, M., McMillan, P. F. (2001). Pressure-induced amorphization and an amorphous-amorphous transition in densified porous silicon. Nature, 414, 528-530.
RAE2008
PY - 2001/11/29
Y1 - 2001/11/29
N2 - Crystalline and amorphous forms of silicon are the principal materials used for solid-state electronics and photovoltaics technologies. Silicon is therefore a well-studied material, although new structures and properties are still being discovered1, 2, 3, 4. Compression of bulk silicon, which is tetrahedrally coordinated at atmospheric pressure, results in a transition to octahedrally coordinated metallic phases5. In compressed nanocrystalline Si particles, the initial diamond structure persists to higher pressure than for bulk material, before transforming to high-density crystals6. Here we report compression experiments on films of porous Si, which contains nanometre-sized domains of diamond-structured material7, 8, 9. At pressures larger than 10 GPa we observed pressure-induced amorphization10, 11. Furthermore, we find from Raman spectroscopy measurements that the high-density amorphous form obtained by this process transforms to low-density amorphous silicon upon decompression. This amorphous–amorphous transition is remarkably similar to that reported previously for water12, 13, which suggests an underlying transition between a high-density and a low-density liquid phase in supercooled Si (refs 10, 14, 15). The Si melting temperature decreases with increasing pressure, and the crystalline semiconductor melts to a metallic liquid with average coordination 5 (ref. 16).
AB - Crystalline and amorphous forms of silicon are the principal materials used for solid-state electronics and photovoltaics technologies. Silicon is therefore a well-studied material, although new structures and properties are still being discovered1, 2, 3, 4. Compression of bulk silicon, which is tetrahedrally coordinated at atmospheric pressure, results in a transition to octahedrally coordinated metallic phases5. In compressed nanocrystalline Si particles, the initial diamond structure persists to higher pressure than for bulk material, before transforming to high-density crystals6. Here we report compression experiments on films of porous Si, which contains nanometre-sized domains of diamond-structured material7, 8, 9. At pressures larger than 10 GPa we observed pressure-induced amorphization10, 11. Furthermore, we find from Raman spectroscopy measurements that the high-density amorphous form obtained by this process transforms to low-density amorphous silicon upon decompression. This amorphous–amorphous transition is remarkably similar to that reported previously for water12, 13, which suggests an underlying transition between a high-density and a low-density liquid phase in supercooled Si (refs 10, 14, 15). The Si melting temperature decreases with increasing pressure, and the crystalline semiconductor melts to a metallic liquid with average coordination 5 (ref. 16).
U2 - 10.1038/35107036
DO - 10.1038/35107036
M3 - Article
SN - 1476-4687
VL - 414
SP - 528
EP - 530
JO - Nature
JF - Nature
ER -