Pressure-induced transformations in amorphous silicon: A computational study

Journal Article · Fri Feb 14 04:00:00 EST 2014 · Journal of Applied Physics

DOI:https://doi.org/10.1063/1.4865274· OSTI ID:22278074

Garcez, K. M. S., ^[1]

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1. Universidade Federal do Maranhão, 65700-000 Bacabal, Maranhão (Brazil)

We study the transformations between amorphous phases of Si through molecular simulations using the environment dependent interatomic potential (EDIP) for Si. Our results show that upon pressure, the material undergoes a transformation from the low density amorphous (LDA) Si to the high density amorphous (HDA) Si. This transformation can be reversed by decompressing the material. This process, however, exhibits clear hysteresis, suggesting that the transformation LDA ↔ HDA is first-order like. The HDA phase is predominantly five-fold coordinated, whereas the LDA phase is the normal tetrahedrally bonded amorphous Si. The HDA phase at 400 K and 20 GPa was submitted to an isobaric annealing up to 800 K, resulting in a denser amorphous phase, which is structurally distinct from the HDA phase. Our results also show that the atomic volume and structure of this new amorphous phase are identical to those of the glass obtained by an isobaric quenching of the liquid in equilibrium at 2000 K and 20 GPa down to 400 K. The similarities between our results and those for amorphous ices suggest that this new phase is the very high density amorphous Si.

• OSTI ID: 22278074
• Journal Information: Journal of Applied Physics, Journal Name: Journal of Applied Physics Journal Issue: 6 Vol. 115; ISSN JAPIAU; ISSN 0021-8979
• Country of Publication: United States
• Language: English

Related Subjects

75 CONDENSED MATTER PHYSICS
SUPERCONDUCTIVITY AND SUPERFLUIDITY
AMORPHOUS STATE
ANNEALING
COMPUTERIZED SIMULATION
DENSITY
EQUILIBRIUM
HYSTERESIS
ICE
LIQUIDS
MOLECULAR DYNAMICS METHOD
PHASE TRANSFORMATIONS
POTENTIALS
PRESSURE DEPENDENCE
PRESSURE RANGE GIGA PA
SILICON
TEMPERATURE DEPENDENCE