High-pressure phases of amorphous and crystalline silicon

Abstract

We study pressure-induced phase transitions in amorphous silicon and crystalline diamond silicon from Gibbs free energies considerations using ab initio total energy calculations. We predict a pressure-induced crystallization of the amorphous network at 2.5 GPa and a first order amorphous to amorphous phase transition at 9 GPa. Furthermore, we find a pressure-induced high density amorphization of crystalline diamond silicon around 15 GPa.

Amorphous structures induced in monocrystalline silicon by mechanical loading

“…26,27 A recent theoretical investigation stated that amorphous structures could be developed in monocrystalline silicon. 28 In this letter, we demonstrate a detailed structural study on the amorphous structures developed in monocrystalline silicon by means of TEM and nanodiffraction.…”

“…This structure is observed as diffuse rings/peaks in the amorphous diffraction pattern. 28 As such, the differences in the diffuse ring structure observed in the three nanodiffraction patterns indicate that there are differences in the atomic structure of the amorphous silicon, over a 1 nm length scale, from which these diffraction patterns were taken.…”

The model developed for stress-induced structural phase transformations of micro-crystalline silicon films

“…Si)=-107.71 eV, E min (ph-Si)=-107.68 eV, and E min (HDA)= -107.53 eV, as obtained from the studies in [23,24,31]. In the present study, B 0 and Bc are the bulk modulus and the pressure derivative of the bulk modulus for silicon with V min, respectively.…”

“…An experiment has recently confirmed such a first order amorphous to amorphous phase transition [22]. Such calculations require candidate structures which may be obtained from constant pressure simulations and sometimes experiments [23,24]. In the present study, a theoretical model is developed …”

“…Here, we examine the atomistic response to nanoindentation by a sharp indenter with various centerlineto-face angles α. From the stress response at incipient plasticity developed by Pan et al [13], the contact stress V c and indentation strain H c in Fig Stress-induced phase transitions in microcrystalline silicon (μc-Si) have been extensively studied [19][20][21][22][23][24]. In order to study the model of crystallization, the volume-dependent Gibbs free energy is evaluated.…”